Root Crops in February

 

Large Smooth Prague celeriac. (Currently sold out Feb 2021)
Photo Southern Exposure Seed Exchange

Root Crops to Plant in Central Virginia in February

We sow no root crops in our hoophouse in February. It’s too late for radishes or turnips. If you are in a place colder or darker than winter-hardiness subzone Zone 7a, with an average minimum temperature of 0° to 5° F (-18°C to -15°C), see Root Crops in January.

If the soil outdoors is dry enough and not frozen, we spread compost on the raised beds we plan to plant in February and March, and till in the compost. Root crops that we sow outdoors here in February include carrots #1 and turnips in mid-February, and carrots #2 and radishes in late February. It’s true not much growing happens in February, but it helps us if we are able to get some crops planted early, leaving us more capacity for other crops once those are in the ground. And if the soil isn’t dry enough, we just do those jobs as soon as we can. We would hate to miss an opportunity!

Carrot Bed Prep

One of our many carrot beds, looking good.
Photo Kathryn Simmons

Carrots do very poorly with competition from weeds or too many other carrots. You can make use of the Stale Seedbed Technique, preparing the bed ahead of time, and flaming or hoeing one or more flushes of weeds as they germinate. I’ll do a separate blogpost on flame-weeding soon, as I have too much info to squeeze in here. It works so well, it feels like cheating!

Carrots are small seeds, needing a fine tilth (small soil particle size and good texture – not likely to crust or blow away).  Good information on crop spacing for maximum yields, or biggest vegetables is in an out of print book, The Complete Know and Grow Vegetables by JKA Bleasdale, PJ Salter, and others. For maximum total yield of carrots, they recommend 1.5” x 6” (4 x 15cm). You get medium sized carrots. For early carrots go with 4 x 6” (10 x 15cm) to minimize competition and get rapid growth. If you want to have rows more than 6” (15cm) apart, calculate the area of these optimum spacings, then divide by your chosen row space. For example, if your rows are 12” (30cm) apart, the carrots can be as close as 0.75’ (2cm) if total yield is more important than individual size, or 2” (5cm) for fast early carrots. We do five rows in a 4 ft (1.2m) bed, so the rows are about 10” apart, with the outer rows 4” (10cm) from the bed edge.

Young Carrot Plants After Thinning. Photo Kathryn Simmons

Carrot Thinning and Weeding

Remember to thin carrots as soon as you can see them well enough to do so. We usually hoe between the rows first, then crawl along thinning and weeding. It does take time! But you won’t get good carrots without thinning, unless you either have a precision-seeder that drops one seed per inch, or pelleted seed which you can sow at one per inch. Precision seeders like the Jang are expensive, but worthwhile if you need to use it every week. Pelleted seed costs more than raw seed, and its big advantage is traded off for two other disadvantages: The soil has to be kept well-watered until germination or else the clay coating will imprison the seed forever, and the seed does not store for long – don’t keep any over for next year.

Greenhouse Root Crop Sowings for Transplants

The only root crops we ever transplant are celeriac and kohlrabi (a stem vegetable really, not a root). I have transplanted many things and I am skeptical of books saying this or that can’t be transplanted, but not beets or rutabagas, which I hear people transplant as soil blocks or plugs. So try it if you think it will help.

Celeriac

Flats of celeriac seedlings.
Photo Kathryn Simmons

We have grown both Diamante (100 days from transplanting) and Large Smooth Prague (110d), and strongly prefer Diamante, as it seems to us to be more tolerant of warm weather, less prone to rot, and easier to clean. Several growers say that Diamante and Brilliant are virtually indistinguishable.

This crop likes rich soil with lots of organic matter, some shade from mid-day and afternoon sun, and ample water without sitting in waterlogged soil. We make sure to choose beds in a shadier part of the garden. Celeriac can rot if too damp, so keep it weeded and remove some of the lower leaves to improve airflow. A pH 5.8-6.7 is ideal. Celeriac can benefit from seaweed as a foliar spray, or side-dressing with compost during the long growing season.

Celeriac requires long steady growth, and the challenge is to prevent checks to growth. The Virginia climate is on the warm side for celeriac, it prefers cooler areas, but we have good success if we pay attention at a few critical times. Celeriac can tolerate frost quite well, so there is no hurry to harvest in the fall.

Sow seeds 1/8″(3mm) deep, and keep the soil surface moist. The minimum germination temperature is 40°F/5°C, and the optimal range 59–70°F/15-21°C. Germination is slow, typically 14 to 21 days, and it takes 10-12 weeks to grow to transplant size, so start in plenty of time. We sow in open flats, then spot out (prick out) into deeper flats. We sow February 10, which is about 10 weeks before our last frost date. Celeriac can be sown from 67 days before the last frost date to 184 days before the first fall frost date, but you don’t get large roots unless you have plenty of growing time.. If your climate includes long chilly springs, I’d suggest starting 12 weeks before the last frost date.

Emergence takes at least 12 days at 59°F/15°C and 7 days at 68°F/20°C. The ideal temperature is 68°F/20°C day, and 59°F/15°C at night. The fluctuating temperatures, with nights cooler than days by 9°F/5°C, help speed germination. Another factor when choosing germination temperature to aim for, is that at 59°F/15°C, only 40% of the seeds produce seedlings, compared to 97% at 68°F/20°C.

Celeriac should not be hardened off by reducing temperatures, as that can cause them to bolt. More than about 9 night temperatures below 55°F/12°C will cause bolting. Plants can have their watering reduced to help them get ready for the big outdoors. Use rowcovers if a cold spell arrives after you have planted them out, or if you know cold weather is likely to return. Falling apple blossom is a phenology sign that conditions are suitable.

See Root Crops in May for transplant info

See SESE’s Celery & Celeriac Growing Guide for growing information.

Kohlrabi

Harvested kohlrabi, Early White Vienna and Early Purple Vienna.
Photo McCune Porter

Kohlrabi is very easy to grow, treat it just like cabbage or kale.

It can be direct-seeded, but for an early crop, especially if you live in a climate like ours where spring turns into summer very quickly, use transplants. We don’t grow a lot, only 180 feet (55m) in total for 100 people. We also grow kohlrabi in the fall, transplanting bare root transplants from nursery seedbeds around August 3. We grow twice as much in fall as spring, because we can store them for winter.

We have grown both Early White Vienna and Early Purple Vienna. Growing both provides for pretty harvests. We sow February 8 at 4 seeds/inch (0.5 cm apart) in open seed flats, aiming to have the plants spotted out, hardened off and transplanted outdoors with rowcover on March 13. Fast work!

Root Crops to Harvest in Central Virginia in February

Hakurei turnips harvested late January.
Photo Pam Dawling

As for January, in central Virginia, there are normally no roots that we could be harvesting outdoors in February except parsnips, Jerusalem artichokes and horseradish.  We do have horseradish, but not the others. Of course, you can only dig up root crops if the ground is not frozen!

We have had outdoor night temperatures of 16°F/-9°C and 12°F/-11°C. This winter we have some carrots “growing” in the fresh air and some late-sown beets under rowcover. I don’t think we’ll get roots from the beets, but the leaves might make a nice change from brassicas as cooking greens.

In the hoophouse our radishes #3 (sown October 30) will come to an end by 2/1. Our #4 radishes will get harvested this month. Our #5 radishes, sown 12/23, will feed us from then until around April 7

We still have some of our first turnips (sown around October 13) until mid-February, and they have reached a really good size, thanks to early thinning. This month we can harvest the second sowing (October 25). We thinned turnips #2 in early January. They are looking good too.

Red Round turnips in our hoophouse in late January.
Photo Pam Dawling

We have not yet needed to unroll our inner rowcovers in the hoophouse. We wait until we expect it to get down to 8°F (-13°C) outdoors, as we like to avoid extra work!

Other Root Crop Tasks in Central Virginia in February

Potatoes stored in crates in our root cellar.
Photo Nina Gentle

Check stored vegetables

Stored crops need to be checked for decay at least once a month, preferably once a week now the days are getting longer and the temperatures will get warmer. From storage, we can eat beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, and turnips, if we grew them.

Special Root Crop Topic for February in Central Virginia

Wrap up the winter planning

Our garden planning wraps up by mid-February, with all the budgets, crew selection and shift decisions (afternoons in cold weather, mornings in hot weather –  we’re mostly half-day gardeners, with one or two stalwart all-day workers)

Order summer cover crop seeds

Buckwheat cover crop in flower.
Photo Pam Dawling

For early spring, if we find an area without a winter cover crop and we realize we won’t plant it with a vegetable crop for at least 8 weeks, we sow oats. They will smother weeds and add organic matter to the soil when you till them in.

If you have not already ordered summer cover crop seeds, this would be a good time to do so. Cover crops suppress weeds, add organic matter, feed the organisms in the soil and attract beneficial insects, birds and amphibians to feed and reproduce. Biodiversity encourages ecological balance that can help reduce plant diseases and pest attacks. Have a goal of No Bare Soil. Seek out odd spaces to fill with cover crops.

Once frosts are past, buckwheat is an easy cover crop. Its flowers attract beneficial insects, and it is a very manageable (not too tall) fast-growing crop. Buckwheat can be in and under in a month.

Just as fast is mustard, but we don’t grow that because it’s a brassica and we grow a lot of brassica food crops. Keeping a good crop rotation is important to us. Also we have harlequin bugs and we don’t want to feed them year round.

Sorghum-sudangrass hybrid is a fantastic, huge warm weather grass type cover crop, but don’t grow it if you have only a lawnmower, a scythe or a nylon line weed whip to cut it down! For smaller scale gardens, choose Japanese millet.

Soybeans, southern peas and sunn hemp are easy legume cover crops for warm weather, providing nitrogen for the next crop.

Cover cropping is a big topic. See my book Sustainable Market Farming for more. Here I’m just pointing you in the right direction enough to order seeds soon. You can read up more later.

Early Lettuce Production

Young Salad Bowl lettuce
Photo Wren Vile

Early Lettuce Production

Growing early season lettuces involves choosing suitable types and varieties (cold-tolerant and fast-growing), having successful production methods, and a good schedule. Harvesting early in the year might mean fast production in January and February, or it might mean starting in the fall and overwintering the plants. See my post series Lettuce of the Month, for ideas on varieties and techniques throughout the year.

Our Climate Zone in central Virginia is 7a, which means our annual minimum temperature averages 0°F to 5°F (-18 to -15°C).  The average date of the last spring frost is April 30 (later than 5/14 one year in 10). We grow lettuce outside from transplants from February to December, in a solar greenhouse from October to early March, and in a solar-heated double-layer hoophouse from October to April.

Swordleaf, Red Salad Bowl and Bronze Arrow lettuces.
Photo Bridget Aleshire

Lettuce Types

There are several different general types of lettuces. In terms of growing speed, the baby lettuce mixes and the leaf lettuces produce harvests soonest after sowing. Loose-leaf lettuces are very useful because you can harvest individual leaves while you’re waiting for the heads to reach full size.

Leaf types are ready for harvest 45-60 days from direct seeding, 30-45 days from transplanting. Bibbs mature in 60-75 days, most head lettuce need up to 80 days from seeding, or 60-70 days from transplanting in spring. Romaines are slower-growing (70 days or more). Batavian lettuces (also called French Crisp) are tasty, thick-leafed varieties that have excellent heat and cold tolerance. Icebergs mature in 75-100 days.

Beautiful baby lettuce mix in our hoophouse.
photo Wren Vile

Baby lettuce can be cut 21 days from seeding, (except from November to mid-February, when it may take 2 or 3 times as long).

Bolt-resistance generally goes from Leaf types (first to bolt), through Romaines, Butterheads, Bibbs, to Crispheads.

I like to sow four lettuce varieties each time (for the attractive harvests, and to reduce the risks if one variety bolts or suffers disease): at least one red and one romaine. We have 5 lettuce seasons, with different varieties:

  1. Early Spring (Jan – Mar), 6 sowings
  2. Spring (April – May 15), 5 sowings
  3. Summer (May 15 – Aug 15), 17 sowings
  4. Fall (Aug 15 – Sept 7), 9 sowings
  5. Winter indoors, Sept 8 – 27, 9 sowings

 Lettuce Varieties

Bronze Arrow lettuce ultra-closeup. Photo Bridget Aleshire

It’s important to grow the right lettuce variety for the conditions. For earliest harvests, consider a different, faster, variety than you have usually grown. Some of the early spring lettuce varieties are often useless here if sown after mid-March, or even mid-February, because they bolt prematurely as the Virginia spring flips from cold to hot (and back again, grrr!). Varieties we only sow until 2/15 include Bronze Arrowhead (46 day leaf lettuce); Buckley, Ezrilla and Hampton (55d multi-leaf types); Merlot (60d), Midnight Ruffles (48d) and Oscarde (45d) (leaf lettuces). Antares (48d) Panisse (48d) and Revolution (38d) leaf lettuces we can sow until 3/15.

Nancy bibb lettuce
Photo Bridget Aleshire

Others that we like in early spring go on to be useful later in spring too. In this category are Buttercrunch (a small 50d bibb); Nancy (58d) and Sylvesta (52d) (two big green bibbs); Pirat (55d red bibb), Green Forest (56d), Kalura (57d) (two green romaines); and New Red Fire (55d), our reliable Salad Bowl (45d) and Red Salad Bowl (46d), Starfighter (52d), and Swordleaf (53d) (leaf lettuces)

New Red Fire lettuce.
Photo by Bridget Aleshire

The baby lettuce mixes we like are Fedco’s 2981 LO Lettuce Mix OG (contains at least six different lettuces) or Johnny’s Allstar Gourmet Lettuce Mix #2310 (including green and red oakleaf, green and red romaine, lollo rossa, and red leaf lettuces). One gram sows 25 ft, one ounce will sow about 600 feet.

For those with challenging growing conditions, both companies offer other specialized selected mixes.

Cold-tolerance of lettuce

Red Tinged Winter and Tango lettuce in our hoophouse in December.
Photo Pam Dawling

Lettuce is more cold tolerant than many people realize. If plants are sufficiently hardened (prepared by growing in gradually lower temperatures), they can withstand freezing. At 22°F (-6°C), large leaves of some lettuce will die. Medium-sized plants with 4-10 leaves (Marvel of Four Seasons, Olga, Rouge d’Hiver, Tango, Winter Density may survive unprotected down to 15°F (-9.5°C). Half-grown lettuces are more cold-hardy than full-sized plants.

Lettuce Crop Requirements

Flats of lettuce transplants in our cold frame in April.
Photo Pam Dawling

Lettuce seed remains dormant unless triggered by adequate levels of light and temperature. It needs light to germinate, so don’t sow too deep: ¼-3/8″ (6-9 mm) is enough. Some sources recommend not covering the seed at all, but this can make it hard to keep the seed damp. The light dormancy is more pronounced in fresh seed, which has higher levels of the hormone that controls germination.

Soil temperature is important. I have a table of optimum soil temperatures for germination in The Year-Round Hoophouse The optimum temperature range for lettuce germination is 68-80°F (20-27°C). It takes 7 days to germinate with a soil temperature of 50°F (10°C) or 15 days at 41°F (5°C), and only 4 days at 59°F (15°C). Even a few hours at temperatures higher than the optimum can induce dormancy.

Lettuce transplants prefer a well-draining soil high in organic matter, and with a pH of 6.0-7.0, not lower. Optimum growing temperatures are 60-65°F (15-18°C), with a minimum of 40°F (4.5°C) for any growth to occur. Lack of water will lead to bolting, and/or bitterness. Keep them growing quickly for good flavor.

Lettuce in January

A flat of newly emerged lettuce seedlings
Photo Kathryn Simmons

We plan to start harvesting heads of lettuce outdoors from April 15. Before then we will harvesting lettuce in our greenhouse and hoophouse.

In mid-January we sow four lettuce varieties, to become our first outdoor transplants. I recommend sowing several varieties each time to spread your risks, if one kind bolts or suffers disease. I choose varieties that cover the range of colors and shapes. I select hardy types that are fast-maturing. Buttercrunch green bibb lettuce is one of my favorites for early spring. One of the Salad Bowl lettuces, red or green, is also usually in my first sowing. The Salad Bowls are so reliable and productive! New Red Fire has become another reliable lettuce stand-by for us. It was suggested to me by neighboring Virginia farmer, Gary Scott of Twin Springs Farm. It is more of a leaf lettuce, and doesn’t exactly head up, although it can be cut as admittedly lightweight heads. It works fine as a leaf lettuce, harvested by the cut-and-come-again method. We grow New Red Fire year round, it’s that adaptable and easy-going. We haven’t found many good full-size red romaines. Bronze Arrow  has worked well for us and we were harvesting it in early May.

We grow all our outdoor lettuce as transplants. In spring we sow in 3″ (7.5cm) deep open wood seed flats, 12″ x 24″ (30 x 60cm). We make four little furrows by pressing a 12″ (30 cm) plastic strip (aka a ruler!) into the seed compost. We sow the seed, label it, cover it lightly, water, and put the seeded flats in our germinator cabinet. The first flat of the year takes about 9 days to germinate.

Spotting cabbage seedlings from a seed flat into a transplant flat.
Photo Wren Vile

Once the seedlings are big enough to handle, we spot them out into 4″ (10 cm) deep flats (also 12″ x 24″/30 x 60cm). We have a plywood dibble board with pegs evenly spaced about 2.5″ (6 cm) apart. We aim to harden off the lettuce for two weeks in the cold frame before transplanting into the garden beds with thick rowcover on hoops to protect the lettuce from the still-cold outdoors. To be ready for harvest 4/15, these seeds have to become full size lettuces in 88 chilly days.

Seeds can instead be sown in cell packs or plug flats, putting three seeds in each cell, and later reducing to one seedling with scissors. Cells or pots with diameters from 1-2½” (2.5-6cm) can be used. The 96-cell size (1×1½”/2.5x4cm) works well, although the 200-cell size (1×1”/2.5×2.5cm) is possible if you can be sure to get the transplants out before they get root-bound. If warm germination space is limited in early spring, sow seed in a small flat, then “spot” the tiny seedlings into bigger flats, 606 (2×2¼”/2.5x6cm) cell packs, or 32-pack square pots to grow on in cooler conditions before planting out. Soil blocks are also possible, but take more time.

We make a second sowing on January 31. The intervals between sowings at the beginning of the year are long, because later sowings will catch up to some extent with earlier ones. Most crops grow faster in warmer weather.

Lettuce in February

We sow lettuce twice in February – 14 days apart. We get ready to transplant our first outdoor lettuce, to feed us mid-late April. Our first sowing of baby lettuce mix in the hoophouse comes to the bitter end, and the second sowing is awaited. We continue to harvest leaves from the large lettuce we transplanted in the hoophouse in October.

Lettuce in March

Lettuce with sclerotinia drop.
Photo Pam Dawling

We sow flats of lettuce every 10 days in March. March 9 is our goal for a transplanting date outdoors for our first 120 lettuce (about one week’s worth for 100 people).

Here is a link to a helpful publication from eXtension: Disease Management in Organic Lettuce Production. Horribly useful photos!

Baby Lettuce Mix

Baby lettuce mix can be ready in as little as 21 days from mid-spring to mid-fall, longer in early spring. A direct-sown cut-and-come-again crop, the plants regrow and can be harvested more than once in cool seasons. We sow 10 rows in a 4’ (1.2m) bed, 4.5” (11cm) apart. Weed and thin to 1″ (2.5 cm). When 3″–4″ (7.5–10 cm) tall, cut 1” (2.5 cm) above the soil. Gather a small handful in one hand and cut with using large scissors. Immediately after harvesting, weed the just-cut area so the next cut won’t include weeds. Rake after harvest with a fine leaf rake to remove outer leaves and cut scraps. If you want to make more than one cut, you will need to remove anything that isn’t top quality salad while you can see it. Larger scale operations have harvesting machines.

 

Root Crops in January

No Root Crops to Plant in Central Virginia in January!

Closing rowcovers after a winter spinach harvest.
Photo Wren Vile

There is nothing, absolutely nothing, in the way of root crops that we sow outdoors here in January. Nor are there any root crops to sow in the greenhouse. Most root crops do not transplant well, as the replanting does too much damage to the taproot. Some exceptions are celeriac and kohlrabi (a stem vegetable more than a root, although I do tend to lump it in with root crops.) I have heard beets can be transplanted, especially if in soil blocks or plugs, and I’ve even heard of people up north transplanting plugs of rutabagas. I tend to be skeptical of books saying this or that can’t be transplanted, as I have transplanted many things. But not yet rutabagas or beets. I did roll my eyes when I heard someone propose transplanting mini-soil-blocks of carrots, using a pair of tongs made with popsicle sticks!

We are in winter-hardiness sub-zone Zone 7a, with an average minimum temperature of 0° to 5° F (-18°C to -15°C).

An Easter Egg radish in the hoophouse in January.
Photo Pam Dawling

Around January 26, we sow our last hoophouse radishes (sowing #6), Easter Egg, and White Icicle. This is our absolute last worthwhile sowing date. They will be ready for harvest from mid-March to mid-April, but if the weather is warm, or we fail to open the doors when we should, they will bolt before we get roots.

Our hoophouse radish sowing dates are 9/7, 9/30, 10/28, 11/22, 12/20, 1/27. Note that the sowing intervals are 23, 28, 25, 28, 38 days. The interval is much longer in December-January, as the rate of growth is so slow. There really is no point in sowing closer to the #5 sowing date, as the #6 will catch up in the warming days of late February and early March. The daylength is also increasing a lot by then, too.

If your hoophouse planting plans exceed the space you have, simply tweaking to a less frequent new harvest start could free up space to grow something else. Also consider a gap in radish supply, if other crops could make better use of the space. See Root Crops in September for more about our succession of hoophouse radish sowing dates.

In our double-layer hoophouse, turnips (and many cooking greens) can survive a hoophouse air temperature of 10.4°F (-12°C) without rowcover, -2.2°F (-19°C) with thick rowcover (1.25oz Typar/Xavan).

January photo of radishes sown in our hoophouse at the end of November.
Photo Pam Dawling

Root Crops to Harvest in Central Virginia in January

In central Virginia, there are normally no roots that we could be harvesting outdoors in January except parsnips, Jerusalem artichokes and horseradish. The months with R in them are the horseradish harvest months. September to April have R in them, and the summer months do not!

We have already had outdoor night temperatures of 16°F/-9°C and 18°F/-8°C. Until temperatures drop to 12°F/-11°C, we could dig Danvers carrots, Cylindra beets, and any rowcovered rutabagas (swedes). Albina Verduna, and Lutz Winterkeeper beets are hardy down to 15°F (-9.5°C), as are most kohlrabi, rutabagas and rowcovered turnips. Covered beets, covered winter radish are OK down to 10°F (-12°C). This is too chancy for us! We like to gather our root crops in and have them safely stored.

We store our root crops washed, in perforated plastic bags, in a walk-in cooler. Root cellars and cool basements are also possible storage sites, and in the past, I stored root crops in boxes of damp sand or woodash.

In the hoophouse we can normally harvest radishes #3 (sown October 30) all through January, from 12/15 to 2/1. This winter I notice we have already harvested most of them (1/6). We harvest our first turnips (sown around October 13) by pulling out the biggest from January 5 (or even late December), until mid-February, by which time we can have made a start on the second sowing (October 25). We thin the second sowing in early January or late December.

Young midwinter turnips in our hoophouse.
photo Pam Dawling

See my list of Winter-Kill Temperatures of Cold-Hardy Winter Vegetables 2020 for a more complete picture of “Harvesting in Time”

Other Root Crop Tasks in Central Virginia in January

Check stored vegetables

From storage, we can eat beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, and turnips, if we grew them. Stored crops need to be checked for decay at least once a month.

Rolls of rowcover in our hoophouse ready to pull over the beds on cold nights.
Photo Wren Vile

Inner tunnels in the hoophouse for cold nights

As noted above, inner rowcovers can make a big improvement to nighttime air temperatures in a hoophouse. We are fortunate to have a climate in central Virginia that means we don’t need inner covers most of the time. We watch the forecast and if we think it will drop to 8°F (-13°C) outdoors, we pull over the rowcovers. For winter crops we don’t use hoops. We have separate lengths of rowcover for each bed. Some people prefer a single large sheet. We find we can set the roll of rowcover at one end of the bed and simply walk with the free end down to the far end of the bed, leaving only a little bit of tweaking to get everything covered.

In the morning, if we feel pretty sure we’ll need the rowcovers again, we just pull the covers into the aisles, leaving every other path free to walk in. If we think we won’t need the rowcovers the next night we roll them up, giving us more space to work, and lengthening the lifespan of the rowcover by not exposing it to much sunlight.

Special Root Crop Topic for January in Central Virginia

Garden Plans Part Two

This garden planning task is not just about root crops. We had our Crop Review in November, and then inventoried our leftover seeds, planned what to grow for next year, and ordered our seeds. See Preparing to order seeds, if you haven’t sent in your orders yet.

We have made our garden maps, and specific plans for important crops with either lots of varieties (tomatoes), lots of sowings (sweet corn) or some combination (lettuce, broccoli and cabbage).

One task we need to complete by mid-January is to prepare our greenhouse seedlings schedule, because here we start sowings in mid-late January. We also tidy up the greenhouse (currently growing lettuce) and test, repair or replace vital equipment (like a seedling heating mat) and supplies like Bt and cover crops seeds.

Tomato seedlings (for our hoophouse) on a heat mat in our greenhouse in February.
Photo Pam Dawling

Another January task is to prepare a new Field Planting Schedule, or Outdoor Planting Schedule, as we call it here to distinguish it from our hoophouse schedule and our seedlings schedule. This is a list in date order of what to sow or transplant, how long the rows are, the space between rows, the space between plants (for transplants) and where to plant.

We also plan crops that will go in our raised beds from January to July. We plan the second part of the year in June, giving ourselves more flexibility.

See my Mother Earth News  Garden Planning online course for details

The map of our raised bed area, showing several years of crops using colored pens.
Photo Pam Dawling

We also revise and update our Garden Calendar (monthly task list). For those who want to think more widely about the coming year, here’s a link to The Complete Twin Oaks Garden Task List Month-by-Month

Our garden planning wraps up by mid-February, with all the budgets, crew selection and shift decisions (afternoons in cold weather, mornings in hot weather –  we’re mostly half-day gardeners, with one or two stalwart all-day workers)

 

Preparing to order seeds

Preparing to order seeds: 6 steps + 3 extra tips

Leeks grow slowly. Sow in March to have seedlings this size in May. Order seed soon! Photo Pam Dawling

There are lots of new gardeners now, as a result of the pandemic causing people to stay at home, cook more and want more food security without going inside grocery stores. Maybe last year you bought packets of seeds in a hurry, either online or off a rack in as store. Maybe you hope your garden will go more smoothly this year and I’m here with this blog post to help you.

Or perhaps you are a new professional grower, seeking to improve your game. Or an established one, looking to hang in there by farming smarter in these hard times.

‘Tis the season for garden planning. Inventory your seeds left from last year, peruse the catalogs and prepare your seed orders. The earlier you get them in, the more likely you are to get the varieties you want, before anything is sold out. Be prepared, note your second choice, and fend off disappointment!

Vates kale seedlings for bare-root transplanting.
Photo Pam Dawling

I have a course on garden planning for home gardeners, on the Mother Earth Fair Online. It consists of eight half-hour workshops, covering all aspects of garden planning from clarifying your goals, choosing crops, making maps of what will go where, planning when you want to harvest, determining how long your rows will be and how much seed to order, deciding when to plant and scheduling everything to make the year go smoothly. There are also workshops on ways to pack more in, and how to be prepared for things that don’t go according to plan!

Mother Earth News Fair

Commercial growers and energetic home growers will also be interested in the information on garden planning in my book Sustainable Market Farming.

I have a couple of slideshows on SlideShare.net,

See Crop Planning for Sustainable Vegetable Production 2019 Pam Dawling

To view it full screen, click the diagonal arrow in the lower right.

For long-term soil health and sustainability, think about crop rotations. See Crop rotations for vegetables and cover crops 2014, Pam Dawling

Buckwheat seedlings. Buckwheat is our quickest easiest summer cover crop.
Photo Pam Dawling

 First, a basic 6 steps of garden planning

  1. See How to Decide Which Crops to Grow.

Think about what you grew last year, and whether you want the same again. Think about what you wished you’d grown. Every year we try to introduce a new crop or two, on a small scale, to see if we can add it to our “portfolio.” Some-times we can successfully grow a crop that is said not to thrive in our climate. (Brussels sprouts really don’t). We like to find the varieties of each crop that do best for our conditions. Later we check how the new varieties do compared with our old varieties. We use heirloom varieties if they do well, hybrids if they are what works best for us. We don’t use treated seeds or GMOs, because of the wide damage we believe they do. For ideas of what you might grow, see our Twin Oaks Harvest Calendar by Crop.

Sowing Rainbow Chard. in a Winstrip tray
Photo Pam Dawling

2. Are any of your leftover seeds OK to keep?

See making an inventory, and Ordering seeds! Seed Viability Many seed catalogs include information about seed longevity, and so does Nancy Bubel in The Seed Starters Handbook. Frank Tozer in The Organic Gardeners Handbook has a table including minimum, average, and maximum.

Seeds stored in glass jars
Photo courtesy of Monticello

A simplified version of how long to keep seeds is as follows:

  • Year of purchase only: Parsnips, Parsley, Salsify, and the rarer Sea Kale, Scorzonera
  • 2 years: Corn, Beans and Peas of all kinds, Chives, Dandelion, Martynia, Okra, Onions,
  • 3 years: Asparagus, Carrots, Leeks, Rutabagas, Turnips,
  • 4 years: Artichokes, Basil, Cardoons, Chard, Peppers, Pumpkins, Spinach, Squash, and Watermelons,
  • 5 years: Beets, most Brassicas, Celery, Celeriac, Chicory, Cucumbers, Eggplant, Endive, Lettuce, Muskmelons, Tomatoes,

Rather than deteriorating with age, some very fresh seed has a dormancy that needs to be overcome by chilling (lettuce).

The fuller story is that storage conditions make a big difference. Keep seed cool, dark, dry in airtight, mouseproof containers.

An old hand-drawn map of one of our garden areas.
Image Pam Dawling
  1. How Much of What to Grow?

Make a rough map of your garden space and see what will fit. Remember you can plant a later crop in the same space after an earlier one finishes. See below for more info on quantities of potatoes and garlic, two staples.

  • How Much Garlic to Plant

A yield ratio of 1:6 or 7 seems typical, and makes complete sense when you consider you are planting one clove to get a bulb of 6–7 cloves. Divide the amount you intend to produce by six to figure out how much to plant. For large areas 750–1,000 lbs/ac (842–1,122 kg/ha) are needed for plantings in double rows, 3″–4″ in-row (7.5–10 cm), beds 39″ (1 m) apart. For single rows, 8 lbs (3.6 kg) of hardneck or 4 lbs (1.8 kg) of softneck plants about 100′ (30 m). In the US, one person eats 3–9 lbs (1.4–4.2 kg) per year.

Music hardneck garlic.
Photo Southern Exposure Seed Exchange
A row of potato seed pieces ready to cover.
Photo by Wren Vile
  1. How Much Seed to Order?

Hopefully you kept some kind of record on whether the amount you bought last year was enough. When we figure out how much seed to order we add in some extra for some things – crops that can be difficult to germinate, or we really don’t want to cut too close. We add 20 percent extra for most crops, but only 5 percent for kale, 10 percent for onions and collards and 30 percent for melons. These numbers are based on our experience – yours might be different. We also know which seed we can buy in bulk and use over several years. This gives us an additional security against poor germination, or plagues of grasshoppers or caterpillars. For me, a big bag of broccoli seed for each of our main varieties gives some kind of warm glow of horticultural security! Buying too much either leads to wasting money (if we throw it away) or wasting time and money (if we sow old seed that doesn’t come up well, then have a crop failure).

If you use spreadsheets, see my post Cooking Greens in December Special Topic: Ordering Seeds.

Here’s a helpful table of 1000 Seed Weight for 13 crops. Another of the challenges with seed ordering is converting between grams, ounces and seed counts – have your calculator at the ready, or easier still, just type “Convert ½ oz to grams”into your search engine.

 

  1. Choosing varieties.

See How to read seed catalogs for tips on getting what you really want by paying attention to what’s in the small print and what isn’t mentioned. We carefully look for varieties that offer the flavor, productivity and disease resistance we need. The catalogs are starting to appear in my mail box. The early bird catches the preferred varieties! The main companies we order from are Fedco Seeds, Johnny’s Selected Seeds and of course, Southern Exposure Seed Exchange. We like SESE for regionally adapted varieties, Fedco for great prices on bulk sizes, and Johnny’s for some varieties we really like that aren’t available from the other two.

 

  1. Formatting and placing seed orders

We grow lots of different crops, so we make a spreadsheet, and include columns for the name of the supplier we buy each variety from (we just use the initial), the item number in the catalog, the packet size and the price. (Be careful though, if you carry this information over from year to year – prices change.) Once we have composed our total seed order, we sort the orders by the name of the supplier. Then we can calculate the total price for each supplier. This also gives us the opportunity to look at price breaks for large orders and move an item from one supplier to another, if that makes sense. At this point we usually make a cup of tea and reward ourselves with an “impulse buy” or two, if that doesn’t push us up into a higher shipping cost bracket or blow the budget. We place our orders online these days, nice and early, to increase the chances of getting exactly what we want.

Here are a few more thoughts on crops to consider:

  1. Insurance crops that are there when you need them

Young Bright Lights chard.
Photo Pam Dawling

For an overall sense of success, grow some “Insurance Crops”. These are reliable vegetable crops that grow without much attention and quietly wait until needed. Chard is one of those. We sow chard in April, after the early spring rush. We plan for it to provide us with leafy greens in the summer, after the brassicas have bolted. We prepare a bed, unroll hay mulch over it, then make “nests” in the hay for planting. Nests are holes in the hay down to soil level, at each spot where we want to plant. After transplanting. we water and tuck the hay tight around the plants to keep the weeds at bay. Some years there isn’t much demand for chard and we just leave it growing. If we need it, there it is with a generous supply of leaves. If we ignore it, nothing goes wrong. It’s worth having some crops like this in the garden, to help ensure there’s always something to eat.

Malabar spinach.
Photo by Southern Exposure Seed Exchange

One year we grew Malabar spinach and it played a similar role: hot weather leafy cooking greens. Malabar can be used when small for salads, or when larger for cooking. It wasn’t hugely popular in either role, but it was beautiful. To be fair, I don’t think we did the best by it. Because it was new, and because it had the word “spinach” in its name, some cooks served large leaves for salad. Alone. I don’t recommend that.

Purple Pod asparagus bean,
Credit Southern Exposure Seed Exchange

Another insurance crop for us is asparagus beans, also known as yard long beans. Once trellised, the plants need no attention, other than regular picking. If not picked, the pods grow puffy and useless, so this is not a crop to ignore for too long. Asparagus beans are related to southern peas (cowpeas), and are more resistant to Mexican bean beetles than regular green beans are. They do need trellising, but once you’ve done that, the same plants will feed you all season. Very little seems to trouble them.

West Indian gherkins on a trellis.
Photo by Nina Gentle

While we’re on the topic of crops that do need trellising, but can then produce all season, I’ll add in the West Indian gherkins. I found I did need to tuck these plants into the netting, so they weren’t work free. But the plants were disease-free and very productive. If you have trouble with regular pickling cucumbers, you might sow some of these as well, to be sure of being able to have something to pickle.

Another insurance crop is Tokyo bekana, or its cousin Maruba Santoh in late summer as a substitute for lettuce. It can be hard to germinate lettuce in hot weather, but these tender brassicas germinate under hot conditions and produce fast-growing very tender leaves with crunchy stems. Some people don’t know they’re not eating lettuce!

Tokyo bekana and spinach in October.
Photo Wren Vile

Senposai is a cooking green that does well in spring and fall outdoors, and in our hoophouse in the winter. It’s fast-growing, productive, disease-resistant, easy to cook and delicious to eat.  In spring it needs an early start in our climate, so that it has time to be productive before it bolts. In fall it’s cold-hardy down to 12F.  Its Achilles Heel is that it can really attract Harlequin bugs! We did spend time every day for a while squashing the bugs on the senposai leaves, and we made a difference in the number of bugs.

Well, I hope this has given you some thoughts about ordering seeds of some insurance crops for next year, when you plan your seed order.

  1. VEGETABLE CROPS THAT OFFER FAST RETURNS

Because things can go wrong in agriculture, (we are, after all, not in control of the universe!) I like to have on hand seeds for fast-growing crops that can fill unexpected gaps.

Some Eat-All Greens in early November.
Photo Lori Katz
  1. Eat-All Greens

Carol Deppe, in her delightful book The Tao of Vegetable Gardening introduces us to the concept of Eat-All Greens. Carol grows these by broadcasting seed of one of her carefully chosen greens crops in a small patch. When it reaches 12″ tall, she cuts the top 9″ off for cooking, leaving the tough-stemmed lower part, perhaps for a second cut, or to return to the soil. I wanted to try this idea in Virginia, where the climate is fairly different from the Pacific Northwest where Carol lives. I decided fall was a promising time of year to try this scheme, as our spring planted greens only have a short season before they bolt. And summer is too hot, winter too cold. . . We sowed in mid-September.

These can also be insurance crops, in that, if you don’t need them, you can cut and compost them, to let fresh leaves grow. I wrote three posts on Eat-All Greens, because they were such fun and so productive

Root Crops in December

Root Crops to Plant in Central Virginia in December

A stormy winter day, garlic, rowcovered spinach beds and our hoophouse.
Photo Wren Vile

Reread Root Crops in October for more ideas of things you might plant, if you are in a much warmer climate zone than us. We are in winter-hardiness subzone Zone 7a, with an average minimum temperature of 0° to 5° F (-18°C to -15°C). We’re not planting anything outdoors in central Virginia in December. But in the hoophouse, we are sowing a couple of things.

Eliot Coleman has given the name Persephone Days to those with less than 10 hours of daylight, when little plant growth happens. Here in central Virginia, the Persephone Days last from November 21 to January 21.  Further north, the period is longer, and it is necessary to grow more of what you want to eat in winter and keep it in a holding pattern to see you through to the other side of the Persephone Days. The holding pattern could be crops in storage, which I wrote about in Root Crops to Plant in Central Virginia in November. Or it could be crops in the ground in a hoophouse.

Temperature also contributes to rate of growth and this is where hoophouse crops score big! It can be a lot warmer during sunny days inside a hoophouse, and our double-plastic hoophouse keeps nighttime temperatures about 8F (4.5C) degrees warmer than outdoors, sometimes 10F (5.5C) degrees warmer. In addition, plants can tolerate lower temperatures inside a hoophouse. The soil stays warmer and the plants recover in the warmer daytime conditions (it seems to be the night+day average temperature that counts). We find, in practice, the period of slowest growth here is December 15 to February 15: still two months long, but lagging the shortest days by three weeks. It takes time for the soil to cool down in late fall and time for it to warm up in early spring.

Hoophouse radishes and Yukina Savoy in December.
Photo Wren Vile

In our double-layer hoophouse, plants without any inner rowcover can survive 14F (7.7C) degrees colder than they could survive outside; with thick rowcover (1.25oz Typar/Xavan) inner covers, at least 21F (11.6C) degrees colder than outside. For example, salad greens in our hoophouse can survive nights with outdoor lows of 14°F (-10°C). Turnips (and many cooking greens) survived a hoophouse temperature of 10.4°F (-12°C) without rowcover, -2.2°F (-19°C) with.

In early December, we sow turnips #3. We sow Hakurei, Early White Egg, Oasis, and Red Round. They will struggle a bit to grow, so they are only worth sowing if we thin them promptly and harvest them on the small size, as the plants will start bolting in early March. See Root Crops in October, for details of thinning and harvesting.

In late December, we sow hoophouse radishes #5, Easter Egg and White Icicle. Cherry Belle and Sparkler types grow too fibrous at this time of year. See Root Crops in September for more about our succession of hoophouse radish sowing dates. Unlike the late October sowing which lasts for 8 weeks, the November sowing will only be good for the (slow-growing) four weeks of February, and this late December one for four weeks from mid-February to mid-March. In this case, it is because the temperature in the hoophouse and the daylength will have increased by then and the radishes will grow fast and start bolting.

Young Red Round turnips in our hoophouse in late November.
Photo Pam Dawling

Root Crops to Harvest in Central Virginia in December

In central Virginia, there are normally no roots that we could be harvesting outdoors in December except parsnips. Jerusalem artichokes are hardy down to 0°F (-18°C), but we haven’t grown those in decades. Horseradish is similarly hardy, but not a mainstay of nutrition. The months with R in them are the horseradish harvest months. This is not woo-woo, it happens that September to April have R in them, and the summer months do not!

Horseradish regrowing up through the mulch in early spring.
Photo Kathryn Simmons

If temperatures have not yet dropped to 12°F/-11°C, we could dig Danvers carrots, Cylindra beets, and any rowcovered rutabagas (swedes). Albina Verduna, and Lutz Winterkeeper beets are hardy down to 15°F (-9.5°C), as are most kohlrabi and rowcovered turnips. But we don’t take that chance. We like to gather our root crops in and have them safely stored. We also like to put our feet up more in December!

Covered beets, covered winter radish are OK down to 10°F (-12°C).

In the hoophouse we can harvest radishes #2 until 12/25, #3 (sown October 30) from 12/15 to 2/1. We harvest our first turnips (sown around October 13) as thinnings from November 29 and by pulling out the biggest from December 5, until mid-February, by which time we can have made a start on the second sowing (October 25).

Turnips in our hoophouse in December.
Photo Wren Vile

See my list of Winter-Kill Temperatures of Cold-Hardy Winter Vegetables 2020 for a more complete picture of “Harvesting in Time”

Other Root Crop Tasks in Central Virginia in December

From storage we can eat (if we grew them!) beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, turnips. Stored crops need to be visited at least once a month and checked for decay.

In our winter squash cage we keep some pancake turners rejected by the kitchen crew. If a squash is having a meltdown, I slide it onto a tray or a bucket lid and throw it outside. The first time I did that this year, I made the mistake of sliding a second squash on top of the first on my bucket lid. The first one couldn’t support the weight of the second. Messy! Sliding them into a bucket would have been safer.

A fine winter squash medley (no, they’re not root crops!)
Photo Southern Exposure Seed Exchange

Special Root Crop Topic for December in Central Virginia

Crop Review and Planning Part One

This is a wider task, not restricted to root crops. In November we have a Crop Review, and then start to plan our crops for next year. We like to get our seed orders in early, to maximize our chances of getting the varieties and quantities we’d like. Some seeds might be in short supply this time, because of all the new gardeners and Covidsteaders that joined our ranks this year.

We consider how well our crops did in terms of plant vigor, disease-resistance, yield, quality, flavor and timing. Did they come in all at once? A benefit for storage crops or those you might sell wholesale. Not so great if you want an extended harvest period.

Planting dates, soil quality, sufficiency (or otherwise) of pest and weed control, plant protection from the elements are all factors that affect yield and crop quality. We can plan to make changes to those things next year. We can decide to plant a different amount, or spread out the planting dates. This can lead to a new calculation of how much seed to buy for the coming year.

By now the seed catalogs are starting to arrive and we can look at what varieties are on offer. Is there a faster-growing turnip? A different carrot we’d like to try? Something with more resistance to the disease we noticed this past year? Something more recommended for our climate or region? While you’re browsing, make a back-up plan if you can’t get your first choice, either from the same catalog, or another.

Hoophouse turnips and baby lettuce mix in December (note the low sun angles!)
Photo Wren Vile

Winter hoophouse growing

 

Hoophouse Yukina savoy at the end of November.
Photo Ethan Hirsh

Last week I wrote about Winter Preparations for Vegetable Gardens. For those with a hoophouse, here are some notes on all the work we can do to grow winter crops there! For those without a hoophouse as yet, scroll to the end for Twenty Benefits of Having a Hoophouse

First, a roundup of previous blogposts on winter hoophouse topics.

Planning winter hoophouse crops includes a description of how we do our hoophouse crop planning so we can maintain a crop rotation and still pack the beds fully with hardy crops.

Fall hoophouse bed prep and shadecloth removal includes spreading compost, broadforking, and a step-by-step guide to hoophouse fall bed prep.

Hoophouse fall bed prep Plans A-D and spider-webs includes some lovely spider photos and a short video of ballooning, as well as info about our first-planted winter crops.

Hoophouse bed broadforked to loosen up slumped soil. I’m happy to say our soil structure has improved in the 18 years since this photo was taken!
Photo Pam Dawling

Young greens in the hoophouse

After the set-backs with our winter hoophouse greens transplants that I wrote about in Hoophouse fall bed prep Plans A-D and spider-webs, we worked really hard and got the whole house planted up. Most of the transplants have recovered from their transplant shock (wilting each day), during the cloudy weather we had.

The new seedlings are coming up fast and calling on us to thin them. We ended up not needing so many of the Plan D plug flat plants, but we’ve kept them for now “in case” .

Plan D: Winstrip seed flats in our hoophouse on Oct 16, a late attempt to catch up!
Photo Pam Dawling

Ultimately if we don’t need them, they’ll go in a salad mix. I wrote about Making baby salad mix last year. The past two days I have been able to harvest a mix in the hoophouse. The ingredient we are shortest of is lettuce. My first mix was spinach, Bulls Blood beet leaves, a few leaves of Tokyo Bekana, Bright Lights chard, Scarlet Frills, Ruby Streaks and Golden Frills, and a handful of lettuce leaves Red Tinged Winter is growing fastest, of all the varieties we planted this year.

Sowing hoophouse winter crops includes some discussion of the tools we like; pre-sprouting spinach seed and growing multi-leaf lettuce.

What’s growing in the hoophouse; reading; planning for winter is an October view of crops.

Frilly Mustards in our Winter Hoophouse is exactly what it sounds like. Four sowings, six varieties. All delicious.

Making baby salad mix includes a discussion of ingredients and methods, balancing nutrition, color, shape and loft.

Young green Panisse and red Revolution lettuce in our hoophouse in November.
Photo Pam Dawling

Cold-tolerant lettuce and the rest, our January 2018 assessment of the varieties we grew that winter and which survived the unusually cold spell we had. Includes sad photos of the casualties!

Also see my Mother Earth News blogpost from August 2018 Grow Great Lettuce in Winter

———————————————————–

Hoophouse seedlings growing outdoors under insect netting. Starting transplants outdoors helps the rotation by reducing the time the crop is growing in the hoophouse
Photo Pam Dawling

Do you value crop rotation in your hoophouse?

In the winter 2019-2020, a reader in the Pacific Northwest wrote: “This winter I have been re-thinking my crop rotation plan after having some issues (with flea beetle larvae in the soil outsmarting my diligent insect netting of my brassica salad crops). These days I see intensive market gardeners seeming to not worry so much about rotation (i.e. Neversink farm, etc), and yet I’ve always been taught that it is such an important principle to follow. I reviewed your slideshows on crop rotation and also cool crop planning in the greenhouse (which briefly addresses salad brassica rotation with other crops). With how much space I have and the high demand I have for brassicas, for salad mix (mustards) and also the more mainstay cole crops, I had settled on a 2.5 yr between brassica crop rotation (but planting two successions of mustards in the same bed within one year, in the year the bed was in mustards, with a lettuce or other crop breaking up the successions, with the idea that they were very short day and also light feeder crops). Wondering if you think this just doesn’t sound cautious enough, or if this sounds like a reasonable compromise with not having more space to work with (and wanting to satisfy the market demand for brassicas).”

I replied: “Yes, I do think crop rotation is important. I do know some farms seem to have given it up. I think what you are seeing shows one reason why rotation is important. In our hoophouse, we do as you do, allocating brassicas to a space for that winter season and perhaps doing more than one round of brassica crops. Then moving away from brassicas for the next two winters. If doing that doesn’t get rid of the flea beetle problem, and you are being thorough about netting with small-enough mesh netting (sounds like you are, but maybe check the mesh size), then my next step would be spinosad when the flea beetles appear. You can spray the inside of the netting too, and close it quickly. It’s that or a longer rotation, which it sounds like is not financially viable. You could also try farmscaping and/or importing predatory insects (not sure if there are any), Are there beneficial nematodes that attack flea beetle larvae? These are things I don’t know about, but might be worth looking into.”


Doing a spot of research today, I find that Heterorhabditis bacteriaphora, (Hb nematodes) a beneficial nematode fromArbico Organics will attack flea beetles. also known as NemaSeek, and sold separately. This is the wrong time of year for introducing nematodes in most of the US. They need warm weather to thrive.

Another suggestion from Arbico is BotaniGard Maxx & other B. bassiana sprays, which infect and kill adult flea beetles. Repeat applications as needed throughout the growing season.

Kaolin clay (Surround) is another possibility.

Also see Harvest to Table on the topic of dealing with flea beetles

———————————————————–

View through the hoophouse doors in December.
Photo Kathleen Slattery

Add a hoophouse to your food production

For those of you wistfully thinking about a hoophouse, let me help you a step closer to having one next year! Sales of my Year-Round Hoophouse book are doing well, which suggests to me that quite a few gardeners and growers are thinking in this direction.

Twenty Benefits of Having a Hoophouse

  1. An extended growing season because plants are protected from cold weather.
  2. Faster growth and higher total yields.
  3. Beautiful unblemished crops not battered by the elements.
  4. Fewer foliar diseases because the leaves can stay dry.
  5. Crop survival at lower temperatures in the hoophouse than is possible outdoors.
  6. Better crop recovery in winter due to warm sunny days following the cold nights.
  7. Some protection from deer and other pests large and small.
  8. Soil temperature stays above 50F (10C) in zone 6b. Warm soil = faster cold weather growth.
  9. Higher proportion of usable crops – more food, higher sales dollars.
  10. Diverse crop portfolio – grow crops that wouldn’t succeed outdoors in your climate.
  11. Harvest whenever you need the crops, even during pouring rain!
  12. Wonderful working conditions – no need for gloves and hats; take off your coat.
  13. A food garden on a manageable scale.
  14. A place to enjoy practicing intensive food production.
  15. The chance to have an area completely free of weeds – new weed seed doesn’t blow in.
  16. No need to work with heavy machinery.
  17. Much better value for producing crops (per dollar invested) than a heated greenhouse.
  18. Can be constructed by generally-handy people. Specialists are not needed.
  19. NRCS grants are available for some hoophouses. Natural Resources Conservation Service, Environmental Quality Incentives Program, High Tunnel System Initiative.
  20. Ecological energy use. The embodied energy of the plastic is less than the energy that would be used to ship similar produce from somewhere warmer (Eliot Coleman, Four Season Harvest). Another study found this was not true for smaller (9 x 12 m) hoophouses – although the economic incentive for growers is still true, there is no energy efficiency advantage to the planet. Smaller carbon footprint: shipping 1 kg lettuce has 4.3 times the CO2 footprint of locally grown hoophouse lettuce. Plawecki, R., Pirog, R., Montri, A., & Hamm, M. (2014). Comparative carbon footprint assessment of winter lettuce production in two climatic zones for Midwestern market. Renewable Agriculture and Food Systems, 29(4), 310-318. doi:10.1017/S1742170513000161.
September sown White Russian kale (transplanted in October).
Photo Wren Vile

———————————————————–

Know your climate

WeatherSpark climate summary for Louisa, Virginia. Go to the website to click for more information

The WeatherSpark website provides “The Typical Weather Anywhere on Earth”. Enter your nearest town or airport and you get clearly explained info with fascinating graphics of how the weather goes over the year in your locality. Note this is not a forecast site, it’s about average weather for each place. Useful to people who’ve recently moved and want to know what to expect this winter, or to new gardeners who haven’t paid so much attention previously. Or to those who want to check their assumptions (I really thought the wind was out of the west more of the time than records say). There are charts of high and low temperature, temperature by the hour each month, cloud cover, daily chance of precipitation (both rainfall and snowfall), hours of daylight, humidity, wind speed and direction and solar energy. A big help in making wise decisions. I know that climate change is going to cause havoc with averages, and we’ll need to learn to become better weather forecasters individually, and to use soil temperature and other metrics to decide when to plant. This website explains things well.

———————————————————–

Winter gives a time for most of us to ponder success, failure, and possibilities for doing things differently.

 

Winter Preparations for Vegetable Gardens

 

Frosty daikon radish
Photo by Bridget Aleshire

Winter-Kill Temperatures

My annual blogpost of Winter-Kill Temperatures for Cold-Hardy Vegetables is always very popular. In fact, it’s my most popular title! Usually searches for this info increase in October and peak in early November, so here are quick links for those of you who have been meaning to look something up.

Winter-Kill Temperatures of Cold-Hardy Vegetables 2020

Winter Kill Temperatures of Cold-Hardy Vegetables 2019

Winter-Kill Temperatures of Cold-Hardy Vegetables 2018

Winter Kill Temperatures of Winter-Hardy Vegetables 2016

Trimming roots from a leek in December.
Photo Pam Dawling

For several years, starting in 2012, my friend and neighboring grower Ken Bezilla of Southern Exposure Seed Exchange and I have been keeping records of how well our crops do in the colder season. Ken provided much of the original information, and has suggested the morbidly named Death Bed idea: set aside a small bed and plant a few of each plant in it to audition for winter hardiness. Note each increasingly cold minimum temperature and when the various crops die of cold, to fine-tune your planting for next year (and leave me a comment!) Each year I update the list, based on new things I learned during the recent winter.

We are in zone 7a, with an average annual minimum temperature of 0-5°F (-18°C to -15°C).

The winter 2019-2020 was mild, with our lowest temperature being a single night at 12°F (-11°C). The Koji greens became completely unmarketable but did not completely die. Yukina Savoy is indeed hardier (as I expected), being OK down to 10°F (-12°C). We had one night at 13°F (-10°C) and two each at 17°F (-8°C), 18°F (-8°C also) and 19°F (-7°C). That winter I noted the death of rhubarb stems and leaves at 25°F (-4°C), rather than 22°F (-6°C), as I noted a year or two ago. I also added some cover crop hardiness temperatures.

Rhubarb in spring.
Photo Kathryn Simmons

I also learned that there is more damage when the weather switches suddenly from warm to cold. And that the weatherman in Raleigh, NC says it needs 3 hours at the critical temperature to do damage. Also note that repeated cold temperatures can kill off crops that can survive a single dip to a low temperature, and that cold winds, or cold wet weather can destroy plants quicker than simple cold. All greens do a lot better with row cover to protect them against cold drying winds.

Winter hoophouse lettuce
Photo Kathryn Simmons

It’s worth noting that in a double-layer hoophouse (8F/5C warmer at night than outside) plants can survive 14F/8C colder than they can outside, without extra rowcover; at least 21F/12C colder than outside with thick rowcover

Salad greens in a hoophouse in zone 7 can survive nights with outdoor lows of 14°F (-10°C). A test year: Lettuce, Mizuna, Turnips, Russian kales, Senposai, Tyee spinach, Tatsoi, Yukina Savoy survived a hoophouse temperature of 10.4°F (-12°C) without rowcover, -2.2°F (-19°C) with. Bright Lights chard got frozen leaf stems.

———————————————–

Seeking Reader Participation

Your experience with your soils, microclimates and rain levels may lead you to use different temperatures. I’d love to hear from readers if they’ve found my numbers work for them, or if they have a different experience. You can leave a comment here, and it will appear on the website, for others to consider. Or you can fill out a Comment Page and only I will see it, although I’ll pass on the information without your name, if I think others would like to know too.

———————————————–

Preparing for winter

Rowcover rolling with crank handle.
Photo Rodaew Institute

I’ve also written posts about winter preparations

Getting ready for frost. This post includes info on DIY weather-forecasting, our Frost Prediction checklist, and our Frost Alert Card. Also a link to a 126 page book which includes explanations of freezes and frosts to help us make sense of advice we’ve not understood. FrostProtectionFundamentalsPracticeandEconomicsFAO.pdf

Preparing for Frost and Cold Weather. This post includes our Frost Alert Card, a Frost Predictions checklist of what to do when the first fall frost is expected; how to use sprinklers overnight to stop tomatoes from freezing; four ranges of cold-hardiness (some crops can wait in the garden till it gets colder); and different levels of crop protection, including rowcover, low tunnels, Quick Hoops, caterpillar tunnels and hoophouses (aka high tunnels).

Season Extension and Frost Preparations. This post includes my Season Extension slideshow; the Frost Alert Card and Frost Predictions checklist again; a diagram of our winter double hoop system to hold rowcover in place during the worst weather;

Double hoop system for winter rowcover.
Pam Dawling

———————————————-

Changing Winter Temperatures

Here’s an article from the Virginia Mercury by Sarah Vogelsong, giving info about changing winter temperatures, particularly later fall frosts in Virginia:

The frozen Potomac River. (Sarah Vogelsong/Virginia Mercury)

Autumn’s first frost is falling later. For farmers, the consequences are wide-ranging

by Sarah Vogelsong, November 3, 2020

Halloween has come and gone. The clocks have been set back. Every evening darkness falls just a little bit earlier.

But for much of Virginia, the first frost still remains elusive.

Over the past century, the average date of the first frost has been moving progressively backward throughout the commonwealth, today landing a week or more later than it did at the turn of the 20th century.

“This is one of the clearest signs of not only the changing climate but … its impact on our systems,” said Jeremy Hoffman, who as chief scientist at the Science Museum of Virginia conducts extensive research on climate change in Virginia. “It’s not just here, it’s everywhere.”

As global temperatures have warmed, largely due to the release of greenhouse gases into the atmosphere, frost seasons have shrunk. The Fourth National Climate Assessment released by the Trump administration in 2018 reported that “the length of the frost-free season, from the last freeze in spring to the first freeze of autumn, has increased for all regions since the early 1900s.”

How the shifts have played out in different states with different geographic, ecological and topographic features varies. Data from the U.S. Environmental Protection Agency show that between 1895 and 2016, the average date of the first fall frost moved back by 7.1 days in Virginia.

On the local level, the changes may be even starker. Estimates of how much the average date has changed vary depending on the time range used and how scientists fit a line to their data points, but in most Virginia cities, they show unmistakable upward trends. Looking at first frost dates between 1970 and 2016, Climate Central, a nonprofit staffed by scientists and journalists, calculated that on average, the first frost today is 5.9 days later in Lynchburg, 8.9 days later in Harrisonburg, 12.8 days later in Roanoke, 15 days later in Charlottesville and 18.5 days later in Richmond. While their data show Norfolk’s first frost occurring about six days earlier on average, Hoffman said that longer-range data going back to 1940 show the first frost moving back by about five days. Still, he cautioned, variation does occur: “Localized things like weather” can “work against that dominant signal in datasets like these.”

First freeze dates for Richmond, 1930-2019. (Jeremy Hoffman, Science Museum of Virginia)

The implications of the shifts in the freezing season go beyond a few more days to enjoy warm weather, say scientists and policymakers. Perhaps most affected are farmers, whose livelihood is intimately tied to fluctuations in both short-term weather and long-term climate.

“Some things you can sort of manage around and some things you can’t,” said Wade Thomason, a professor of crop and soil environmental science at Virginia Tech and the state’s grain crops extension specialist.

For most farmers, the last frost of the year in the spring is the riskier of the season’s two endpoints, falling as it does when most plants are young and more vulnerable to temperature extremes. But ongoing changes in the first frost in the fall also have ripple effects.

“It can be a beneficial thing for some instances. We might get more grazing days for livestock operations in a year,” said Thomason. For some crops, like double-cropped soybeans that are planted following the harvest of another crop — typically a grain like wheat — “it can extend the season.”

Other effects are less immediately apparent. Many wheat farmers who typically plant in mid-October have begun to push back their planting dates to ensure plants don’t grow too quickly during the freezing months, making them susceptible to disease or falling over in the field. Specific types of forage rely on long periods of cool weather to thrive: in Northern Virginia and the Shenandoah Valley, farmers have noticed that orchard-grass stands are only living for four to five years instead of the once-standard 10.

“For years now, we’ve heard from farmers that the stands don’t persist like they used to,” said Thomason. Research has shown that one factor contributing to less persistence is warmer nighttime temperatures, he added, but because most operations rely on cultivars developed decades ago, “we haven’t adapted orchard grass that thrives in a warmer climate.”

Other crops affected by longer warm seasons? Tree fruits and wine grapes

“Virginia’s one of those places that we expect to get hotter and we also expect to get wetter,” said Benjamin Cook, a climate scientist with the National Aeronautics and Space Administration’s Goddard Institute for Space Studies whose research includes the effects of climate change on vineyards. Neither of those conditions are necessarily good for high-quality wine prospects, he said. Furthermore, farmers working in these areas face special risks because of the long time to maturity of their crops.

“Those are parts of the agricultural world that adaptation eventually becomes a lot more challenging, because you can’t switch crops from year to year,” he said. “You have to make a bet on something and wait four years to see if it pays off.”

Regardless of their specialty, all farmers face another consequence of shorter freeze seasons: more weeds and more pests.

“With longer growing seasons, with these warmer winters, the populations of insects are increasing, the mortality is lower, they can produce more generations a year, and that potentially presents a problem for agriculture and plants in general,” said Cook.

Those effects can be seen on the ground, said Thomason: “Maybe 30 years ago, we could stop worrying about them in early October, and now it may be a week or 10 days later.”

https://www.virginiamercury.com/ Virginia Mercury is part of States Newsroom, a network of news outlets supported by grants and a coalition of donors as a 501c(3) public charity. Virginia Mercury maintains editorial independence. Contact Editor Robert Zullo for questions: [email protected] Follow Virginia Mercury on https://facebook.com/thevirginiamercury and https://twitter.com/MercuryVirginia

Our stories may be republished online or in print under Creative Commons license CC BY-NC-ND 4.0. We ask that you edit only for style or to shorten, provide proper attribution and link to our web site.

———————————————-

Root Crops in November

Root Crops to Plant in Central Virginia in November

We have reached the slow-growing time of year. We have passed our last chance to sow root crops outdoors. Nothing changes fast. Reread Root Crops in October for more ideas, if you are in a warmer climate zone than us. We are in Winter-hardiness zone 7, which has overall minimum average of temperatures of 0° to 10°F (-18°C to -12°C). We are in subzone Zone 7a, with a minimum average temperature of 0° to 5° F (-18°C to -15°C).

In late November, we sow our fourth radishes in our hoophouse. See Root Crops in September for more about our succession of hoophouse radish sowing dates. We sow Easter Egg, and White Icicle. It is too late for us to sow Cherry Belle or Sparkler types – they get too fibrous. This sowing will feed us for the month of February. Unlike the late October sowing which lasts for 8 weeks, this sowing will only be good for 4 weeks.

See Root Crops in September for information on figuring sowing dates for winter hoophouse succession crops (radishes are the example)

Late September in our hoophouse: radishes, scallions and new transplants in the beds on either side. Photo Wren Vile

In early November (around 11/9), we often sow our second of three plantings of hoophouse turnips. We sow Hakurei, Early White Egg, Oasis, and Red Round. These will be harvested 2/25-3/10 (with thinnings for greens from 1/11).

Sometimes we make our second sowing in late October, if we have space available then and want bigger turnips. We may make a third turnip sowing in very early December if space opens up then. The third sowing is only worthwhile if thinned promptly and eaten small, as the plants will start bolting in early March.

See Root Crops in October, for details of thinning and harvesting.

Root Crops to Harvest in Central Virginia in November

Large Smooth Prague celeriac.
Photo Southern Exposure Seed Exchange
Florence bulb fennel. Photo
Southern Exposure Seed Exchange

 

 

 

 

 

 

If you are unsure how soon temperatures will drop in your area, see Weatherspark

Enter your city, airport or zipcode and you’ll get access to helpful graphics on seasonal temperatures, cloud coverage, rainfall, snow, sunshine, humidity, wind, water temperature at nearby large bodies of water. Also tourism, which I had not previously thought of as a type of weather! After that comes an assessment of growing conditions (considered only as days without frost) and growing degree-days, solar energy, and more.

In Louisa County, where we are, the average daily low temperature in November makes a precipitous but erratic slide from 45°F (7°C) to 36°F (2°C), with a small chance of going as low as 24°F (-4°C) by the end of November. Most of our root crops other than sweet potatoes and potatoes can wait to be harvested until late November, but we would rather proceed with harvesting and storing, as the daylight gets shorter and the chance of cold, wet working conditions get higher.

Green kohlrabi.
Photo Small Farm Central

 

We continue clearing root crops outdoors and storing them (in this order): 

  • ·         25°F/-4°C, bulb fennel
  • ·         20°F/-7°C, turnips, winter radish, celeriac
  • ·         15°F/-9°C, kohlrabi, beets (15-20°F/-9 to -7°C, depending on variety)
  • ·         12°F/-11°C, carrots, Cylindra beets
  • ·         10°F/-12°C, parsnips, probably OK to 0°F (-18°C)
  • ·         Horseradish is not killable by cold temperatures, as far as I can tell. But if the ground is frozen, you can’t dig it up.

Wash and store roots in perforated plastic bags under refrigeration, or in a root cellar or other cold storage place.

Our 9/6 sowing of hoophouse radishes will have finished and our second sowing will mature and brighten our meals from 11/6 to 12/25 approximately. Our first sowing of hoophouse turnips (10/15) will produce edible little roots as thinnings later in the month.

See Washing, sorting and storing root crops in Root Crops in September.

See my list of Winter-Kill Temperatures of Cold-Hardy  Vegetables 2020 for a more complete picture of “Harvesting in Time”

Other Root Crop Tasks in Central Virginia in November: Long term storage of sweet potatoes and white potatoes

Sweet Potatoes in storage.
Photo Pam Dawling
Sweet potatoes

After curing, store boxes of sweet potatoes at 55-60°F (13-15.5°C), 50-60% humidity. Curing is complete when the skin is undamaged after rubbing two together. If the heating in your curing space is variable, be sure to check several boxes of sweet potatoes closer to and further from the heater. We once had a sad thing happen after a new heater had been installed. We were checking the most accessible boxes only, not the ones at the back near the heater. We got wrinkly sweet potatoes. If your crop is not curing as fast as you hoped, check the temperature, and do what you can with fans to move the air around without blasting directly on any particular box. Also check the humidity and adapt as needed. We found that splashing water directly on the concrete floor of our basement was the most successful method.

 

Restack the boxes (in a rodent-proof storage cage, if you are using an outbuilding).

Peruvian (“white”) potatoes

 

Potatoes stored in crates in our root cellar.
Photo Nina Gentle

Sort white potatoes in storage 2 weeks after harvest. See Root Crops in August

Root Cellar: Cool to 50°F (10°C) after one month, then 40°F (4.5°C), airing once a week or less if cooling not needed. See Special Topic for July

Special Root Crop Topic for November in Central Virginia Vegetable storage without electricity.

  • ·         Meeting the storage requirements of various crops helps maximize their season of availability
  • ·         Some vegetables need to cure before storage and the curing conditions are different from those needed for storage. Curing allows skins to harden and some of the starches to convert to sugars.
  • ·         Many crops may be stored without electricity, perhaps in buildings that serve other uses at the height of the growing season.

  • ·         Washington State University Extension’s Storing Vegetables and Fruits at Home, is a good introduction to alternatives to refrigerated storage, using pits, clamps and root cellars. Drawings below are from WSU Storing Vegetables and Fruits at Home
  • ·         Also old versions of the USDA Agriculture Handbook 66.
Home vegetable storage options, from WSU
Four Sets of Storage Conditions

 By providing storage spaces with 4 types of conditions, 25 crops can be stored.

  • ·         In my chart in Sustainable Market Farming, the Summary column indicates the general conditions needed for each crop, and allocates each crop to one of 4 groups:
  • ·         A= Cold and Moist: 32°F–40°F (0°C–5°C), 80%–95% humidity — refrigerator or winter root cellar conditions. Most roots, greens, leeks
  • ·         B= Cool and Fairly Moist: 40°F–50°F (5°C–10°C), 85%–90% humidity — root cellar. Potatoes
  • ·         C= Cool and Dry: 32°F–50°F (0°C–10°C), 60%–70% humidity — cooler  basements and barns. Garlic and onions
  • ·         D= Warm and Dry to Fairly Moist: 50°F–60°F (10°C–15°C), 60%–70% humidity — basements. Sweet potatoes and winter squash.
Our winter squash storage cage. Photo Twin Oaks Community
Winter squash and pumpkins – storage

We built a rodent-proof cage with wood shelves. You could use shallow crates to avoid handling each individual squash.

In-ground protected vegetable storage. WSU
In-ground storage

Depending on the severity of your winter, some cold-hardy root crops (turnips, rutabagas, beets, carrots, parsnips, Jerusalem artichokes and horseradish) and also leeks can be left in place in the ground, with about 12” (30 cm) of insulation (straw, dry leaves, chopped corn stalks, or wood shavings) added after the soil cools to “refrigerator temperatures.”

 Hooped rowcovers or polyethylene low tunnels can keep the worst of the weather off. There could be some losses to rodents, so experiment on a small scale the first winter to see what works for you. We have too many voles to do this with carrots or turnips.

Besides being used as a method for storage of hardy crops deep into winter, this can be a useful method of season extension into early winter for less hardy crops such as beets, celery and cabbage, which would not survive all winter this way. Access to crops stored in the ground is limited in colder regions — plan to remove them all before the soil becomes frozen, or else wait for a thaw.

Vegetable storage clamp WSU
Storage clamps (mounds)
  • Cabbage, kohlrabi, turnips, rutabagas, carrots, parsnips, horseradish, Jerusalem artichokes, salsify and winter radishes (and any root vegetables that can survive cold temperatures) can be stored with no electricity, by making temporary insulated outdoor storage mounds (clamps).

Mark a circular or oval pad of soil, lay down straw, pile the roots up, cover them with straw and then with soil, digging a drainage ditch round the pile. For ventilation, leave a tuft of straw poking out. Slap the damp soil in place to protect the straw and shed rainwater.

For the backyarder, various roots can be mixed, or sections of the clamp can be for different crops. Those growing on a large scale would probably want a separate clamp for each crop. It is possible to open one end of a clamp or pit, remove some vegetables, then reseal it.

 There is a balance to be found between the thermal buffering of one large clamp and the reduced risk of rot that numerous smaller clamps provide.

WSU vegetable storage in a buried bin.
Pits and trenches

Dig a deep, wide pit (3+ feet deep) in a dry area where water will not stand, lining it with heavy plastic and straw. Alternate layers of vegetables with layers of straw, finishing with straw. Put a loose sheet of plastic on top, (not sealed down). Cover with more soil.

To deter rodents, bury large bins such as (clean) metal trashcans, layer the vegetables inside with straw, and cover the lid with a mound of more insulation and soil.

Or bury insulated boxes in the ground inside a dirt-floored shed or breezeway. A new life for discarded chest freezers! Insulated boxes stored in unheated areas need 6-8” (15–20 cm) of insulation on the bottom, sides and top.

Root Cellars for crops needing cool, damp conditions

  • ·         Potatoes do best in a dark cellar, at 40° – 50°F (5° -10°C). With a good in-ground root cellar, potatoes store for 5-8 months. Ventilate as needed, to maintain the cellar in the ideal range.
  • ·         Below 40°F (5°C) the starches convert to sugars, giving potatoes an unpleasant flavor and causing them to blacken if fried.
  • ·         Root cellars can be used for apples, cabbage, or root vegetables, but be careful what you mix.
  • ·         Some people pack the unwashed roots in boxes of sand, wood ash, sawdust or wood chips. Perforated plastic bags or crates are easier.
  • ·         Pepper plants can be hung upside down in a cellar to ripen, or store. Cabbage can also be hung upside down.
  • ·         Cabbage, celery, leeks can be replanted side by side in boxes or tubs of soil.
Our root cellar for potatoes. Photo McCune Porter
Ethylene

Ethylene is generally associated with ripening, sprouting and rotting. Some crops produce ethylene gas while in storage — apples, cantaloupes and ripening tomatoes all produce higher than average amounts. Environmental stresses such as chilling, wounding and pathogen attack can all induce ethylene formation in damaged crops. Some crops, including most cut greens, are not very sensitive to ethylene and so can be stored in the same space as ethylene-producing crops. Other vegetables, however, are very sensitive to the gas and will deteriorate in a high-ethylene environment. Potatoes will sprout, ripe fruits will go over the top, carrots lose their sweetness and become bitter.

 

Vegetable harvests, articles on seed saving and garlic planting, workshop on cover crops.

 

Close up of Cow Horn okra pods.
Photo Kathryn Simmons

There are several aspects of vegetable harvesting. In this post I will look first at maturity indicators, then at four ranges of cold-hardy crops for harvest at various stages of winter, followed by a reminder of the order for harvesting storable crops, according to the coldest temperature they can take. After that I have links to a couple of other websites with great information on these topics, a mention of two articles on seed saving  and one on garlic planting I have in Growing for Market magazine. And a link to a Mother Earth News Fair Online workshop on establishing winter cover crops.

Harvest and Maturity Indicators

Don’t harvest too soon or too late. How do you know when it’s ready to harvest? Different factors are important for different crops. Use all your senses.

  • Size: Cow Horn okra at 5”/13 cm (others shorter), green beans a bit thinner than a pencil, carrots at whatever size you like, 7”/18 cm asparagus, 6”/15 cm zucchini
  • Color: Garden Peach tomatoes with a pink flush. The “ground spot” of a watermelon turns from greenish white to buttery yellow at maturity, and the curly tendrils where the stem meets the melon to turn brown and dry. For market you may harvest “fruit” crops a bit under-ripe
  • Shape: cucumbers that are rounded out, not triangular in cross-section, but not blimps. Sugar Ann snap peas get completely round before they reach peak sweetness.
  • Softness or texture: eggplants that “bounce back” when lightly squeezed, snap beans that are crisp with pliable tips. Harvest most muskmelons when the stem separates easily from the fruit (“Full slip”).
  • Skin toughness: storage potatoes when the skins don’t rub off, usually two weeks after the tops die, whether naturally or because of mowing.
  • Sound: watermelons sound like your chest not your head or your belly when thumped. Try the “Scrunch Test” – press down firmly on the melon and listen and feel for the separation of the ripe flesh inside the melon.

Cabbages are fully mature when the head is firm and the outer leaf on the head is curling back. Ignore the separate “wrapper leaves” when making this judgment. If you need to keep mature cabbage in the ground a few days longer, twist the heads to break off some of the feeder roots and limit water uptake, and they will be less likely to split.

Mature cabbage showing curled leaf on the head.
This educational photo of a split cabbage is provided by Firesign Farm

Broccoli
Select blue-green broccoli heads and harvest them before the flower buds open, but after they’ve enlarged. We press down with finger-tips and spread our fingers to see if the head is starting to loosen.

Young immature broccoli head after rain
Photo Wren Vile

Sweet Corn

Sweet corn will be ready to harvest about three weeks after the first silks appear. Corn is ready when the ears fill to the end with kernels and the silks become brown and dry. An opaque, milky juice will seep out of punctured kernels. You can use your thumbnails to cur through the husk on the side and view the kernels. Don’t make your cut on top of the ear, or the dew and rain will get in and rot the corn.

Sweet corn ears are mature when the silks die and turn brown. Photo Kathryn Simmons
Mature Sweet corn ear.

Garlic

Garlic is ready to harvest when the sixth leaf down is starting to brown on 50% of the crop. See Ron Engeland’s Growing Great Garlic. Harvesting too early means smaller bulbs (harvesting way too early means an undifferentiated bulb and lots of wrappers that then shrivel up). Harvesting too late means the bulbs may “shatter” or have an exploded look, and not store well.

Cut across hardneck garlic – airspaces around the stem show maturity

Music garlic cut open showing gaps around stem – a sign of maturity.
Photo Southern Exposure Seed Exchange
Garlic bulb cut horizontally to check maturity (good now or soon).
Photo Wren Vile

Onions

Wait until the tops fall over to harvest, then gently dig up the whole plant and dry. Leave the dry, papery outer skin on the onion for protection.

Onions curing and drying in strings. Photo by Southern Exposure Seed Exchange

Four Ranges of Cold-Hardy Crops for Harvest at Various Stages of Winter

  1. Crops to keep alive into winter to 22°-15°F (-6°C to -9°C), then harvest. Harvest and use soon: Asian greens, broccoli, cabbage, chard, lettuce, radishes. Harvest and store: beets, cabbage, carrots, celeriac, kohlrabi, winter radish (including daikon), rutabagas, turnips. Many greens and roots can survive some freezing, so it is worth experimenting to find how late you can keep crops outdoors.
  2. Hardy winter-harvest crops: cabbage (Deadon), carrots, collards, kale, leeks, parsnips, scallions, spinach. We grow our winter-harvest crops in our raised bed area, which is more accessible in winter and more suited to small quantities.
  3. Overwinter crops for spring harvests before the main season. Some crops, if kept alive through the winter, will start to grow again with the least hint of spring weather and be harvestable earlier than spring plantings. Depending on your climate, the list can include carrots, chard, chicories such as radicchio and sugarloaf, chives, collards, garlic, garlic scallions, kale, lettuce, multiplier onions (potato onions), scallions, spinach. In mild areas, peas can be fall sown for a spring crop. Sow 1″ (2.5 cm) apart to allow for extra losses.
  4. Winter hoophouse crops: The rate of growth of cold-weather crops is much faster inside a hoophouse than outdoors. The crop quality, especially with leafy greens, is superb. Plants can tolerate lower temperatures than outdoors; they have warmer soil around their roots, and the pleasant daytime conditions in which to recover. Salad greens in a hoophouse can survive nights with outdoor lows of 14°F (–10°C) without inner rowcover.

In my post Root Crops in October, I gave this list of storable crops in the order for harvesting, related to how cold they can survive.

Clear and store (in this order):

  • Sweet potatoes 50°F (10°C)
  • “White” Peruvian potatoes 32°F (0°C) approximately
  • Celeriac 20°F (°C)
  • Turnips 20°F (°C)
  • Winter radish 20°F (°C)
  • Beets 15-20°F (°C)
  • Kohlrabi, 15°F (°C)
  • Carrots 12° F (°C)
  • Parsnips 0°F (°C)

———————————–

Here are some links to a couple of good sources for more harvest information:

  1. Piedmont Master Gardeners Garden Shed Newsletter

Guidelines for Harvesting Vegetables by Pat Chadwick

A list of seven basic principles of harvesting, followed by a crop-by-crop list of almost 50 individual crops and a resource list of 18 publications (focused on the mid-Atlantic and Southeast)

  1. October Tips from Harvest to Table, by Steve Albert covers all climate zones and comes complete with a USDA Hardiness Zone Map

Prepare your garden for colder weather, plant winter crops where there is still time, harvest crops that will suffer from cold, construct low tunnels with rowcover or clear plastic to keep crops somewhat protected from wind and cold temperatures

Links to other posts by Steve Albert

How to Prepare a Winter Vegetable Garden

Predicting Frost in the Garden

Garden Tips for October


Growing for Market articles

Harvesting seeds this fall?

I have written articles for Growing for Market magazine about growing and saving seeds (August and September issues), and planting garlic (October issue).

Given the shortages of some varieties this spring, it wouldn’t surprise us if more people tried producing seeds of vegetable or flower varieties this year. Here are links to articles from the August and September magazines, covering wet and dry seed processing.

Roma tomatoes cut in half for seed extraction.
Photo Pam Dawling

Wet seed processing and saving

Wet seeds are embedded in fruit. Wet processing has four steps: scooping out the seeds or mashing the fruit, fermenting the seed pulp for several days, washing the seeds and removing the pulp and then drying the washed seeds.

Read the article “Wet seed processing and saving”

Dry seed processing and saving

Dry seeds develop in pods, husks or ears, and dry on the plant rather than inside a fruit. While you obviously want to get seeds into the hands of growers before they need to plant, and into seed catalogs before they get printed, often there is no urgency to extract the dry-seeded crops from their pods. You can wait for a slower time, or use seed cleaning as a rainy-day job.

Read the article “Dry seed processing and saving”

—————————————————

Mother Earth News Fair

I have a workshop on Winter Cover Crops for Gardeners as part of the Mother Earth News Fair Online Winter Gardening Course. The Winter Gardening Course features 7 videos, each 21-44 minutes long. Mine’s 32 minutes on cover crops.

You can enroll for the 8-course Winter Gardening Course for $20.

Or choose the 2020 all-access course bundle of 21 courses (over 100 videos) for $150.

 

 

 

 

 

 

 

 

 

 

Sweet potato harvests over the years

Crew harvesting sweet potatoes. Photo Wren Vile

 In my 10/30/20 post Growing High Yielding Sweet Potatoes, I wrote

When to harvest sweet potatoes

Unlike white potatoes, which have the annual plant sequence of vegetative growth, flowering and dying back, sweet potato plants would go on growing forever if the weather remained warm enough. Choose when to dig them up, ahead of cold weather. The longer you wait, the bigger the potatoes, but you are gambling with the weather. Usually sweet potatoes are harvested in the week that the first frost typically occurs in your region. I have written plenty already in previous years about harvesting, so I won’t go into it here. See one of the links to those posts, or my slideshow, if you want to know what comes next, or your climate is considerably colder than mine in central Virginia.

Today I looked to see the “plenty” I had written in previous years, and was surprised not to find much! Every mid-October from 2012 to 2016, I mentioned sweet potato harvest, but many times it has been in passing, and mostly yield statistics (bragging or groaning). 2012 has the most detail on doing the harvest – read it below.

In 2019 we got a very nice yield and carried on eating sweet potatoes into September. Previously people seemed to lose interest in sweet potatoes in late May, and we would distribute our surplus to other people. This year we just kept eating and enjoying them. I can report that they did get wrinkly and grow big sprouts, but were still very tasty down to the last one in late September.

We now use electric fencing to keep the deer out, and grow on biodegradable plastic mulch to keep the weeds down, and use drip irrigation to grow the sweet potatoes up. These developments in our method became necessary over the years.

Yesterday we ate sweet potato leaves as a seasonal green. You can eat these throughout the growing season, but we usually don’t, as we hesitate to take away anything that is helping the tubers grow. But at harvest time, the leaves are about to return to the soil, so we clipped the vine tips and cooked them up. OK, interesting, never going to be a favorite for me, but perfectly acceptable, and less distracting than going off to harvest somehting else to eat in the middle of the big sweet potato harvest!

Sweet potatoes ready to crate up.
Photo Nina Gentle

Sweet Potato Harvest October 2016

10/11/16: Yesterday we started harvesting our sweet potatoes. Yields look OK but not fantastic. We had a lot of problems with deer eating our sweet potatoes this year. We did have a temporary electric fence, but we often didn’t pay it good attention and it grounded out. Next year the rotation brings the sweet potatoes to a more traveled location. I can’t believe I’m already doing that “Gardener Survival Strategy” of thinking “Next Year Everything Will Be Perfect”!!

 10/18/16: Our average first frost date is October 14. Actually from our own records it has averaged 10/22 over the last 11 years. . . .  It’s good to be prepared.

This post includes tips on DIY weather-forecasting, and preparations for fall frosts

Sweet potatoes sorted into boxes.
Photo McCune Porter

 Sweet Potato Harvest 2015

 10/20/15: We got our sweet potatoes all dug and safely indoors before Saturday night’s 27F and Sunday night’s 26F. Whew! Another Garden Year Milestone passed. We got about 223 boxes this year. The boxes contain about 23lbs each, so that’s 5129 lbs, plenty to feed 100 hungry people for six or seven months. . . .  Our average harvest for this size patch (about 700 plants) is 4035lbs. This year we got a yield of a little over 7lbs of sweet potatoes per plant. Last year’s record crop was 11lbs per plant.

 10/13/15: We are on the point of harvesting our sweet potatoes. After all the rain we had recently, we were waiting for the soil to dry enough to walk on. . . . I was worried for a couple of days that the weather would stay cold and the sweet potatoes might rot in the cold wet soil. One year when I was fairly new to Virginia I caused us to leave the sweet potatoes in the ground till early November (hoping they would grow a bit more) and then it rained hard and we ended up with a load of sweet potatoes that either rotted directly or else went through a transition to a hard uncookable state. I learned the hard way to harvest sweet potatoes before soil drops to 55F. This week I studied the soil thermometer and the max and min thermometer and was reassured by the warm sunny days. The soil has been drying out nicely. Tomorrow we start digging. It usually takes us three afternoons. Everything looks auspicious. No rain or horribly cold weather, enough people. . .

Crates of sweet potatoes selected for growing next year’s slips.
Photo Nina Gentle

Sweet Potato Harvest 2014

10/14/14: Our sweet potato harvest is huge this year! We mostly managed to keep the deer out of the plot, by luck and a scarecrow and things that fluttered in the breeze. We’ve filled all our usual boxes and then scrambled twice to find more! . . . . I counted the equivalent of 273 normal-sized boxes in the basement this morning. At 23 pounds for our standard box, that’s about 6280 pounds. We might be up to 6500 pounds by the time we’re done. This will be our record! I think our local food pantry will be getting some sweet potatoes this winter and next spring!

I compared sweet potato yields for different years. We usually have about 600 plants in 800 row feet (16″ spacing). Yield is about 11 pounds/sweet potato plant this year. But as they say “your results may vary.”  Ours certainly have. Working back from 2012, we harvested 4070 lbs, 2208 lbs, 1860 lbs, “lots” (poor record-keeping!), 5590 lbs, 3820 lbs and 4050 lbs in 2007.

Hauling sweet potatoes uphill the hard way. Sometimes we use the truck!
Photo Nina Gentle

Sweet Potato Harvest 2013

10/13/13, Sweet potatoes, statistics and inspiration: After a week of drizzle, it finally eased up and we started harvesting our sweet potatoes. . . .  As usual, we set the dug roots in clusters, so we could see which plants yielded most and chose medium-sized roots from those to grow our slips next year. . . . This year, the Georgia Jet seem more productive than the Beauregard – I think that’s usual. We dug about a third of the crop the first day and got 86 boxes. The second day we had a lot of other harvesting (beans and broccoli being the most time-consuming), so we only dug another 36 boxes. . . .

Well  . . .  the yield dropped off a lot where the deer had been browsing (memo: fence out the deer in future!) We got a total of 177 boxes of various sizes, perhaps about 3939 pounds, almost two tons. . . .

Our yearly harvest of sweet potatoes has varied a lot, from 31 boxes (a sad year) to 243 in 2009. An average over ten years of 112 boxes, each weighing perhaps 23 pounds. . . .  We always hope to have enough to last till the beginning of May, when people start to lose interest in sweet potatoes, and start hoping for tomatoes.

Sweet potato harvest.
Photo Nina Gentle

How we do our Sweet Potato Harvest 2012

10/12/12: Usually sweet potatoes are harvested the week the first frost typically occurs. . . . Contrary to myth, there is no toxin that moves from frozen leaves down into the roots. On the other hand, cold injury can ruin the crop, and roots without leaf cover are exposed to cold air temperatures, and have lost their method of pulling water up out of the soil. Cold wet soil can quickly rot sweet potatoes (I know, it’s happened here).

To harvest, we first remove the vines from the area to be harvested that day. There is usually 3 afternoons’ digging for ours, and we want to leave live vines to protect the rest of the crop overnight. We use pruners to snip the vines where they emerge from the soil, leaving stumps to show where to dig. We roll the vines into the spaces between the rows.

Using digging forks, we carefully dig up the roots, which grow in the ground in a bunch-of-bananas shape. We want to select good potatoes for seed, and we grow several different kinds (Georgia Jet, Beauregard, and a couple of heritage varieties whose names we don’t know), so we make sure not to mix potatoes from different rows. As we dig, we set the potatoes out beside the spot where they’ve grown, one clump per plant, so it’s easy to identify the most productive plants.

It’s important not to bruise the roots, or to leave them exposed to temperatures higher than 90°F (32°C) for more than half an hour, or they will get sun-scald. Below 55°F (13°C), they’ll get chilling injury. We also avoid any abrasion of the skin, which is very fragile at this stage. We leave the sweet potatoes to dry on the ground for 1-2 hours, unless the weather is unsuitable. This year we had ideal weather, not too hot, not too cold, breezy enough to dry the skins, sunny.

We want to grow our own slips (baby plants) next year, so we save at least 1 root per 5 slips wanted.  (1 good slip every 16″.) So to plant 800 row feet, (600 slips), we save 100 each of our two main varieties and 20 each of the two heirlooms. That should be plenty. Some will shrivel or rot, so we allow a margin. We don’t save for seed any roots that look diseased. We choose plants with a high yield and no string (rat-tail) roots. From these plants, we choose small-medium sized potatoes with typical shape and color.

When grading and crating the roots in the field, we first choose the seed potatoes, and then sort storable from “Use First” roots. Large open broken surfaces will cure and can be stored, but any roots with soft wet damaged areas or deep holes (whether from voles, bugs or fork tines) will not store, and should be graded out, for composting or immediate use. We sort into 4″ deep wood flats or 5″ plastic crates for curing, and buckets for the “Use First” category.

Boxes of sweet potatoes curing.
Photo Nina Gentle

Immediately after harvest, we take the boxes of sweet potatoes into a warm damp basement below the dining hall, to cure. This allows the skin to thicken, cuts to heal over and some of the starches to convert to sugars. Uncured “green” sweet potatoes are not very sweet at all, and are better used in dishes where they combine with other foods. A baked uncured sweet potato is a sad disappointment.

We stack our boxes of roots on pallets, and put wooden spacer sticks between boxes in each stack, to ensure airflow. We get quite good temperatures, but keeping humidity up is difficult for us. We cover the flats with newspaper to hold in some moisture. The best result seems to come from splashing water on the concrete floor several times each day. We use box fans to improve the airflow, and the basement already has some natural ventilation.

Ideal conditions for curing are 85-90°F (29-32°C), and 80-95% humidity for 4-7 days, with some airflow and ventilation. Curing takes longer if conditions are less than perfect. The length of the curing period also varies with the dryness of the soil just prior to harvest. We usually reckon on 10-14 days. . . . .

So – how did we do this year? Middle of the road, I’d say. Decent yields, but not a bumper crop – we still had empty boxes left over. The deer were regularly eating our vines until quite recently. Last year we had a dog to chase the deer off, but he met with a road accident. His replacement was old, and she just wanted to be a pet, so we had deer again. We used drip irrigation and biodegradable plastic mulch this year, and did a good job of weeding, so I put the lower yields down to deer damage.

Sweet potatoes on a plate.
Photo Brittany Lewis