Winter Kill Temperatures of Cold-Hardy Vegetables 2019

Baby greens in a cold frame in January.
Photo Southern Exposure Seed Exchange

I keep records of how well our crops do in the colder season, both outdoors and in our double-layer hoophouse. I note each increasingly cold minimum temperature and when the various crops die of cold, to fine-tune our planning for next year. We are in zone 7a, with an average annual minimum temperature of 0-5°F (-18°C to -15°C).  We had some extremely cold temperatures of -8°F and -9°F (-22°C and -23°C) in early January 2018. The winter of 2018-2019 was not as brutal. Our lowest temperatures were 6°F (-14°C) 1/31/19, 8°F (-13°C) 12/11/18 and a couple of 11°F (-12°C). This year I found that senposai is  more cold-tolerant than I had thought. otherwise I haven’t got much new news here. My results from other years hold up.

Unless otherwise stated, these are killing temperatures of crops outdoors without any rowcover. All greens do a lot better with protection against cold drying winds. Note that repeated cold temperatures can kill 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. Your own experience with your soils, microclimates and rain levels may lead you to use different temperatures in your crop planning.

Hoophouse Notes

Our double-plastic hoophouse keeps night time temperatures about 8F (4.5C) degrees warmer than outdoors, sometimes 10F (5.5C) warmer. Plus, plants tolerate lower temperatures inside a hoophouse. The soil stays warmer; the plants recover in the warmer daytime conditions (it seems to be the night+day average temperature that counts);

Winter crops snug in our hoophouse in a December snowstorm.
Photo Pam Dawling

In the hoophouse (8F warmer than outside) plants without extra rowcover can survive 14F colder than they could survive outside; with thick rowcover (1.25oz Typar/Xavan) at least 21F colder than outside.

For example, salad greens in our hoophouse can survive nights with outdoor lows of 14°F (-10°C). Russian kales, lettuce, mizuna, senposai, spinach, tatsoi, turnips, 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.

Lettuce varieties for a solar-heated winter greenhouse or hoophouse in zone 7a: (hardiest are in bold) Buckley, Ezrilla, Green Forest, Green Star, Hampton, Hyper Red Rumpled Wave, Marvel of Four Seasons, Merlot, New Red Fire, North Pole bibb, Oscarde, Outredgeous, Pirat, Red Cross bibb, Red Sails, Red Salad Bowl, Red Tinged Winter, Revolution, Rouge d’Hiver, Salad Bowl, Sylvesta bibb, Tango, Winter Marvel, Winter Wonderland.

Hoophouse lettuce Red Tinged Winter and Tango (and senposai) in our hoophouse in December.
Photo Pam Dawling

Outdoor killing temperatures of crops (unprotected unless stated)

35°F (2°C):  Basil.

32°F (0°C):  Bush beans, cauliflower curds, corn, cowpeas, cucumbers, eggplant, limas, melons, okra, some pak choy, peanuts, peppers, potato vines, squash vines, sweet potato vines, tomatoes.

27°F (-3°C): Many cabbage varieties, Sugarloaf chicory (takes only light frosts).

 25°F (-4°C): Some cabbage, chervil, chicory roots for chicons, and hearts, Chinese Napa cabbage (Blues), dill (Fernleaf), endive (Escarole more frost-hardy than Frisée), some fava beans (Windsor), annual fennel, some mustards (Red Giant, Southern Curled) and Asian greens (Maruba Santoh, mizuna, most pak choy, Tokyo Bekana), onion scallions (some are much more hardy), radicchio.

22°F (-6°C): Some arugula (some varieties are hardier), Bright Lights chard, large leaves of lettuce (protected hearts and small plants will survive colder temperatures), rhubarb stems and leaves.

20°F (-7°C): Some beets (Bulls Blood, Chioggia,), broccoli heads (maybe OK to 15°F (-9.5°C)), Brussels sprouts, some cabbages (the insides may still be good even if the outer leaves are damaged), celeriac, celtuce (stem lettuce), some head lettuce, some mustards/Asian greens (Tendergreen, Tyfon Holland greens), flat leaf parsley, radishes (Cherry Belle), most turnips (Noir d’Hiver is the most cold-tolerant variety).

Large oat plants will get serious cold damage. Oats seedlings die at 17°F (-8°C)

Canadian (spring) field peas are hardy to 10-20°F (-12 to -7°C).

Closing rowcovers after a winter spinach harvest.
Photo Wren Vile

15°F (-9.5°C): Some beets (Albina Verduna, Lutz Winterkeeper), beet leaves, some broccoli, some cabbage (Kaitlin, Tribute), covered celery (Ventura), red chard, cilantro, endive, fava beans (Aquadulce Claudia), Red Russian and White Russian kales, kohlrabi, some lettuce, especially medium-sized plants with 4-10 leaves (Marvel of Four Seasons, Olga, Rouge d’hiver, Tango, Winter Density), curly leaf parsley, rutabagas (American Purple Top Yellow, Laurentian) if not covered, broad leaf sorrel, most covered turnips, winter cress.

12°F (-11°C): Some beets (Cylindra,), some broccoli, Brussels sprouts, some cabbage (January King, Savoy types), carrots (Danvers, Oxheart), most collards, some fava beans (mostly cover crop varieties), garlic tops if fairly large, most fall or summer varieties of leeks (Lincoln, King Richard), large tops of potato onions, covered rutabagas, some turnips (Purple Top).

Using a sturdy digging fork to harvest leeks in December.
Photo Pam Dawling

10°F (-12°C): Covered beets, Purple Sprouting broccoli for spring harvest, a few cabbages (Deadon), chard (green chard is hardier than multi-colored types), some collards (Morris Heading can survive at least one night at 10F), Belle Isle upland cress, some endive (Perfect, President), young Bronze fennel, probably Komatsuna, some leeks (American Flag, Jaune du Poiteau), some covered lettuce (Pirat, Red Salad Bowl, Salad Bowl, Sylvesta, Winter Marvel), covered winter radish (Daikon, China Rose, Shunkyo Semi-Long survive 10°F/-12°C), Senposai leaves (the core of the plant may survive 8°F/-13°C), large leaves of savoyed spinach (more hardy than smooth-leafed varieties), Tatsoi, Yukina Savoy.

Oats cover crop of a medium size die around 10°F (-12°C). Large oat plants will die completely at 6°F (-17°C) or even milder than that.

Garlic shoots poking through the mulch in January.
Photo Pam Dawling

5°F (-15°C): Garlic tops even if small, some kale (Winterbor, Westland Winter), some leeks (Bulgarian Giant, Laura), some bulb onions, potato onions and other multiplier onions, smaller leaves of savoyed spinach and broad leaf sorrel. Many of the Even’ Star Ice Bred greens varieties are hardy down to 6°F (-14°C), a few unprotected lettuces if small (Winter Marvel, Tango, North Pole, Green Forest).

0°F (-18°C): Chives, some collards (Blue Max, Winner), corn salad (mâche), garlic, horseradish, Jerusalem artichokes, Even’ Star Ice-Bred Smooth Leaf  kale, a few leeks (Alaska, Durabel, Tadorna); some bulb onions, yellow potato onions, some onion scallions, (Evergreen Winter Hardy White, White Lisbon), parsnips (probably even colder), salad burnet, salsify (?), some spinach (Bloomsdale Savoy, Olympia). Walla Walla onions sown in late summer are said to be hardy down to -10°F (-23°C), but I don’t trust below 0°F (-18°C)

Crimson clover is hardy down to 0°F (-18°C) or slightly colder

Vates kale with a freeze-killed center January 19 2018. Photo Pam Dawling

 -5°F (-19°C): Leaves of overwintering varieties of cauliflower, Vates kale survives although some leaves may be too damaged to use.

Many of our Vates kale plants survived those cold temperatures Photo Pam Dawling

-10°F (-23°C) Austrian Winter Field Peas and Crimson clover (used as cover crops).

-15°F (-26°C) Hairy vetch cover crop – some say down to -30°F (-34°C)

-20°F (-29°C) Dutch White clover cover crops – or even -30°F (-34°C)

 -30°F to -40°F (-34°C to -40°C): Narrow leaf sorrel, Claytonia and some cabbage are said to be hardy in zone 3. I have no personal experience of this.

 -40°F (-40°C) Winter wheat and winter rye (cover crops).

A hardy cover crop mix of winter rye, hairy vetch and Austrian winter peas.
Photo Bridget Aleshire

What can you do if spring is too wet?

Our kale beds after heavy rain. Photo Wren Vile

As growers, we do not have control over everything that happens. The main thing outside of our control is the weather, and it’s only going to get more chaotic as climate change bites. Heavy rain events can leave soil impossible to work, because the water can’t drain away fast enough. What can we do when it’s too wet?

Laura Lengnick in Resilient Agriculture views climate change as yet another production risk to assess and prepare for. The vulnerability of your farm has two components: exposure and adaptive capacity. As far as exposure, the most immediate key exposure is water issues (too much and too little). As for adaptive capacity, the main feature is our personal capacity to respond and plan. We need to pay greater attention to the climate as a critical factor in our decision-making.

Be Prepared

  • See Weatherspark.com for easy-to-understand graphics showing the average weather in your locality. Figure out which crops are most marginal already in your climate, and decide whether they are worth keeping in your crop portfolio, and whether they are important enough to be worth providing more protection for.
  • Using raised beds can help excess water to drain sooner.
  • Raised beds will drain and be ready to plant sooner after rain.
    Photo Ezra Freeman
  • Increasing the organic matter content of the soil helps it absorb more water in a manageable way, without compacting and going anaerobic. Compost improves the soil structure, organic matter and humus. The effects last longer than cover crops and crop residues, especially in humid conditions where the breakdown of plant material is very rapid.
  • Maximize the volume of living roots (food crops and cover crops) throughout the soil profile (use both deep-rooted and shallow-rooted crops).
  • Cover crops. The root channels improve the soil structure — fine roots make up 70% of the root biomass of crimson clover, vetches, and field peas, and when the cover crops are mowed, these roots support microbial growth, form active organic matter, and rapidly release N to the plants. Keeping roots in the soil all the time, or as much of the time as possible, will help prevent erosion.
  • Consider no-till cover crops which become mulch.

    A no-till cover crop mix of winter rye, hairy vetch, Austrian winter peas and crimson clover.
    Photo Bridget Aleshire
  • Avoid “bare fallow” at times of year when you could get a lot of rain. That might mean not just hurricane season, but year-round. Low-growing non-invasive cover crops can be planted in pathways.
  • Minimize tillage because tilling accelerates nutrient burn-up and hence the loss of organic matter. Avoid tilling or disking right before a forecast of heavy rain.
  • If water drainage is a big issue where you are, you may need to consider a “grassed waterway” Your NRCS office can help with the design. See their publication Grassed Waterway and Vegetated Filter System, Conservation Practice Job Sheet 412. This is really a very large gradual swale with a grassed surface, which you can mow (think home-grown mulch!).
  • Another option is a “drywell” or French drain, a big hole full of rock. We calculated that for our hoophouse, ours would need to be 11′ × 11′ (3.4 × 3.4 m) and 4′ (1.2 m) deep. It would have been a big area and a lot of rock (and money), and not inconsiderable maintenance to keep it free of sediment and leaves.
  • Field tile drainage
  • Keyline plowing (along contours).
  • Swales (also called “infiltration trenches”) allow water to gradually seep into the soil, while sending sudden large volumes downhill to an area which can absorb more water. A swale 18″ (45 cm) wide by 8″ (20 cm) deep in averagely draining soil can infiltrate approximately 1.6″ (4 cm) rain per hour per 20 ft2 (1.86 m2) of contributing area.

    A caterpillar tunnel and a plastic mulched bed at Potomac vegetable Farms in November.
    Photo Pam Dawling
  • Physically cover the soil: hoophouses and caterpillar tunnels can help keep crops from deluges. Large structures do have the issue of runoff, but you can plan ahead for that and make a drainage system. When we built our hoophouse, we made a ditch around three sides of it, to channel runoff downhill. Some people who have roll-up or drop-down sidewalls install plastic guttering on the “hipwall” lumber that these structures need, and collect the rainwater for irrigation. Bear in mind that the water catchment barrel will be low down and the water will need pumping or dipping and hauling to be useful. Read the NRCS Code 558 Roof Runoff Structure.
  • Before the storm moves in, cover the soil where you plan to plant: temporary caterpillar tunnels (field houses), low tunnels, plastic mulches and tarping (occultation) can keep some of the soil dry, at the expense of causing runoff that makes other areas wetter. This can help get crucial plantings done in a timely way, leaving the wider problem to resolve later.
Fast-growing Red Salad Bowl lettuce.
Photo Bridget Aleshire

First Aid if you can’t plant when you want to

  • Consider transplanting instead of direct seeding. We did this one year with our winter squash, when the plot was hopelessly too wet. We were able to transplant the squash fairly young, and did not have a big harvest delay.
  • Consider a different, faster, variety that you can sow later and catch up. Some leaf lettuces only need 46 days (Salad Bowl, Bronze Arrowhead, Tom Thumb), while Romaines can take a lot longer (Crisp Mint, Winter Wonderland 70 days, Webb’s Wonderful 72 days). Baby lettuce mix can be ready in as little as 21 days from mid-spring to mid-fall.
  • Consider a different, faster, crop that you can sow or transplant later. Keep your crop rotation in mind, as well as the next crop you intended to plant in that spot. Here are some fast-growing crops:
    • Ready in 30–35 days are some Brassicas such as kale, arugula, radishes (both the fast small ones and the larger winter ones); many Asian greens (Chinese Napa cabbage, Komatsuna, Maruba Santoh, mizuna, pak choy, Senposai (40 days) tatsoi, Tokyo Bekana and Yukina Savoy). See my Asian Greens of the Month category of posts
    • One summer we sowed Tokyo Bekana as a lettuce substitute. 20 days to baby size, 45 days to a (large) full size.
    • Also ready in 30–35 days are spinach, chard, salad greens (lettuce, endives, chicories) and winter purslane.
    • Ready in 35–45 days are corn salad, land cress, sorrel, parsley and chervil.
    • Ready in 60 days are beets, collards, kohlrabi, turnips and small fast cabbages (Farao or Early Jersey Wakefield).
  • The International Cooperators’ Guide Grafting Tomatoes for Production in the Hot-Wet Season recommends using eggplant rootstocks for tomatoes when flooding is expected.

First Aid if you can’t till

  • Could you mow? This will prevent weeds seeding, and prevent the cover crop or previous food crop from getting any bigger. It will be easier to till once that does become possible.
  • If you can’t get a mower across the beds, can you use a weed whip (string trimmer) or a manual weed whacker or a scythe? This will buy you some time.
  • Could you use a broadfork? This will open up the soil, allowing it to dry faster.
  • Could you lay tarps over the whole mess, and wait for the cover crop or weeds to die?
  • Could you use a flame weeder to kill the existing vegetation? Flamers are intended to kill small weeds, not big ones, but we successfully used our wand-type flamer to kill weeds in the potato patch one spring when it was too wet to hill the potatoes.
Flaming (pre-emergent)
Photo Brittany Lewis

Dealing with Floods

  • If your soil floods, drain it promptly, or you may end up with drowned plants (insufficient air) and with a high salt level caused by evaporation. Dig shallow trenches to let the flood water flow away.
  • After the flood recedes, you could lose yield from loss of soluble nutrients. The soil may have become anaerobic, reducing available nitrogen. If you have a suitable source of nitrogen, apply some. You may also get a flush of weeds, competing with your slow-to-recover crop.
  • See How to Rehab Your Soil after a Flood on the Hobby Farms website for five steps to repairing the damage: Clean Up, Remove Water, Beware of Contamination, Level the Land, Rebuild the Soil with Cover Crops. See also the Carolina Farm Stewardship Association’s Expert Tip: How to Handle Flooded Fields for information about food safety.
  • Consult your local Extension service before selling any produce that has been in standing water, as the water may have become contaminated. See the US Food and Drug Administration Guidance for Industry: Evaluating the Safety of Flood-Affected Food Crops for Human Consumption
  • There is more about dealing with floods  and disasters in general, in The Year-Round Hoophouse.

Sustainable Farming Practices slideshow, Mother Earth News blogposts, Modern Farmer

Greenhouse interior with early spring seedling flats.
Photo Kathryn Simmons

I just got home from the Organic Growers’ School Spring Conference near Asheville, NC. On Friday, I gave an all-day workshop with Ira Wallace, on Year-Round Growing on the Farm and Garden. The classroom at Creekside Farm, Arden was packed. This farm also has an educational center, which made a great setting for our workshop. The weather was awful, so we didn’t explore the very wet farm much. We had plenty of indoor teaching material including show-and-tell. The funniest part was my Julia Child chicken-on-the-floor moment when I dropped a freshly -made soil block on the nice wood floor.

On Saturday and Sunday, I gave  my Sustainable Farming Practices presentation, which is now on www.SlideShare.net, and posted here for convenient viewing. Just click the diagonal arrow icon to see it full screen.

Now I have a couple of lovely days at home, working in the hoophouse and greenhouse. The crew is steadily composting more beds, sowing peas and transplanting endless spinach beds (our spring is short and then heats up, so to get a longer spring spinach season, we do all transplants.)

Summer Lettuce Nursery Seedbed with Concept, De Morges Braun, New Red Fire and Loma lettuces.
Photo Bridget Aleshire

My post 20 Tips for Success in Germinating Seeds in Hot Weather was #8 in the top blogposts for 2018. My newest post on Mother Earth News Organic Gardening blog is

We transplant all our spring spinach, to maximize the length of the harvest period
Photo Denny Ray McElyea

The Pros and Cons of Direct Sowing and Transplanting

One of the pages in our Field Manual, which we revise each winter.
Photo VABF

In early January I posted 13 Steps to Planning your Vegetable Garden

Elsewhere for interesting gardening and farming reading, I am enjoying The Modern Farmer an online and digital subscription magazine with lots of thought-provoking and useful articles. Some recent ones I really like include

Can Hydroponic Farming Be Organic? The Battle Over The Future Of Organic Is Getting Heated.

Does Milk Actually Make Kids Grow Taller?

Trump Administration Rolls Back School Nutrition Standards

Ten Great Farming Podcasts to Listen to Now

America’s First Cash Crop: Tobacco

Urban Gardening 101: How to Deal with Contaminated Soil

My next speaking event is the Virginia Festival of the Book,and then the Mother Earth News Fair in Asheville, NC. There I’m presenting Lettuce Year Round and Cool Season Hoophouse Crops. Here’s the probable schedule. This is a change from what I posted earlier. I”m replacing Cold-Hardy Winter Vegetables with a new one, Cool Season Hoophouse Crops.

Hoophouse beds in November.
Photo Ethan Hirsh

 

Alliums for March: transplant bulb onions, harvest garlic scallions, ramps, minimize onion bolting

Flats of March-sown leek seedlings in our coldframe in early April.
Photo Pam Dawling

Allium Planting in March

  • Divide and replant Egyptian onions and perennial leeks, during March or April
  • Sow leeks in flats, coldframes, or raised beds. See below
  • Transplant fall-sown bulb onions early in the month. see Alliums for November and February. More info below
  • Transplant cipollini seedlings. Cipollini, also known as pearl or boiling onions, are varieties of short day onions sown in spring, planted at high density, which form small bulbs and mature in a couple of months.
  • Plant shallots Jan-Feb.
  • Plant softneck garlic cloves or bulbs for garlic scallions. See Alliums for February
Garlic scallions ready for harvest.
Photo Wren Vile

Allium Harvests in March

  • Start harvesting garlic scallions (3/10 to 4/30 in central Virginia). See below for more details
  • Harvest hoophouse scallions (our 10/20 sowing Feb 20- mid-Mar and our 11/18 sowing from mid-March.)
  • Harvest leaves of Egyptian onions & perennial leeks, Sept- April
  • Harvest winter leeks Dec- March. See Alliums for January and Alliums for November
  • Harvest ramps, sustainably for one month, from when tree buds appear (late March or early April in the Appalachians). Ramps are a spring ephemeral of deciduous forests. By late May, the leaves die back and a flower stem emerges. Wild ramps are being over-harvested, and it is important to make sure that not all these wild culinary delights vanish and they are still able to find their way onto plates in a sustainable fashion. See
Harvested ramps.
Photo Small Farm Central

Alliums to Eat from Storage in March

  • Eat softneck garlic from storage once all the hardneck has been used (softneck stores longer)
  • Eat bulb onions from storage, including bulbils from Egyptian onions if you stored those.

Alliums to Weed in March

All overwintered alliums will need weeding in March and once a month after that until harvest. Mulched crops can be weeded during wet weather, if necessary, and the pulled weeds can be discarded on top of the mulch, where they stand a much better chance of dying then weeds discarded on bare soil! It is helpful to have a list of tasks that can be done when the soil is wet, in case of a wet spring (or any season really). Perennial crops and annuals with mulch are the main jobs for this list (along with tool repair and sharpening).

Newly planted alliums in bare soil will benefit from hoeing during dry weather before the weeds get very big at all. Hoe every 1-4 weeks as needed until harvest. Because of their vertical tubular or strap-like leaves, alliums do not compete well with broadleaf weeds and can easily become stunted in high weeds. We learned the hard way one year when our leek beds grew very big weeds. Even though we did pull the weeds, the leeks never grew very big. As well as the competition for light, we think our huge weeds pulled too many nutrients from the soil. After that, we acknowledged the wisdom of growing fewer leeks and taking care of them better, rather than over-extending ourselves.

A fine bed of onions in spring.
Photo Kathryn Simmons

Special Allium Topics for March: Sowing leeks, transplanting onions, harvesting garlic scallions, onion bolting factors

Sowing leeks

Calculate how many leeks of each variety you want to harvest, add a margin. Each of our 90 ft (27.5 m) raised beds takes 4 rows of leeks, with plants 6″ (15 cm) apart. That’s 720 plants per bed. We sow in 24″ (60 cm) long flats, aiming for 3 seeds per inch (<1 cm apart). With 6 rows per flat, we need 1.67 flats/bed with no extras. We’ll call that 2 flats per bed.

We don’t need heat to start the leek seedlings, only time, so we put the flats directly into the coldframe. The minimum temperature for leek germination is 35F (), the optimum 65-85F () and they take 8-16 days just to germinate, even at the ideal temperature. Alliums are so slow! I always allow at least 10 days.

Leeks take 10-12 weeks to grow to transplant size. We sow ours March 21 for June 1 transplanting, which is only 10 weeks. When we grew them in a raised bed, it took 12 weeks. We like Lincoln and King Richard for leeks to eat in October and November and Tadorna for over-wintering, to eat December-February.

Transplanting onions

Transplant fall-sown onions as early in spring as possible, and those sown after New Year once they have at least three leaves (four or five is better). The final bulb size is affected by the size of the transplant as well as the maturity date of that variety. The ideal transplant is slightly slimmer than a pencil, but bigger than a pencil lead. Onion seedlings are slow-growing: even in spring they can take ten weeks to reach a size suitable for transplanting. Overly large transplants are more likely to bolt. If seedlings are becoming thicker than a pencil before you can set them out, undercut two inches (5 cm) below the surface to reduce the growth rate. Or use them as scallions.

Some books recommend trimming the tops at transplanting time, but I used to avoid this because I believed it reduces the yield. I forced myself to test out this idea one year, and found I got the same yield from trimmed and untrimmed onions. Trimmed ones are easier to plant. Transplant 4″ (10 cm) apart for single seedlings or 12″ (30 cm) for clumps of three or four (not more than four). Set plants with the base (stem plate) 1/2″–1″ (1.3–2.5 cm) below the soil surface. Some books recommend as deep as two inches (5 cm). Don’t plant too shallowly. Give plenty of water to the young transplants: keep the top 3″–4″ (8–10 cm) of the soil damp for the first few weeks to prevent the stem plate from drying out.

Onion bed in late April.
Photo Kathryn Simmons

Harvesting garlic scallions

With a last frost date of 20–30 April, we harvest garlic scallions from early March until May, if our supply lasts out, and we don’t need the space for something else. Harvesting is simple, although depending on your soil, you may need to loosen the plants with a fork rather than just pulling. Trim the roots, rinse, bundle, set in a small bucket with a little water, and you’re done!

Some people cut the greens at 10″ (25 cm) tall and bunch them, allowing cuts to be made every two or three weeks. We tried this, but prefer to simply lift the whole plant once it reaches about 7″–8″ (18–20 cm). The leaves keep in better condition if still attached to the clove. Scallions can be sold in small bunches of three to six depending on size. If you do have more than you can sell in the spring, you could chop and dry them, or make pesto for sale later in the year.

Onion bolting factors

Onions are cool-season plants. They have three distinct phases of growthvegetative, bulbing and blooming (bolting), and the switch from one phase to the next is triggered by environmental factors. It does not work to plant onions at a random date in the year without taking account of these environmental factors. Success depends on understanding what this crop needs during each of the three phases. To get a full understanding of the three phases and the factors that cause plants to switch to the next phase, see the Bulb Onions chapter of my book, Sustainable Market Farming.

Continue reading “Alliums for March: transplant bulb onions, harvest garlic scallions, ramps, minimize onion bolting”

Succession Planting Slideshow, Organic Growers School, Virginia Festival of the Book

Here’s an updated version of my slideshow Succession Planting for Continuous Vegetable Harvest, which I presented at the Pennsylvania Association for Sustainable Agriculture Conference a couple of weeks ago. The website lists the 2020 conference now, which will also be at the Lancaster Convention Center.

My next speaking event is the Organic Growers School at Mars Hill University, Asheville, NC on Friday–Sunday, March 8–10, 2019. It’s their 26th Annual Spring Conference. On Friday I’m giving an all-day workshop with Ira Wallace:

Year Round Growing on Farm & Garden

Pam Dawling & Ira Wallace

Join experienced vegetable, herb, and seed growers Pam Dawling & Ira Wallace for a step-by-step approach to growing year-round. Learn the tools to manage space effectively, grow the quantities of crops when you want them, and efficiently meet your growing goals.

Where: Creekside Farms Education Center, 339 Avery Creek Road, Arden, NC 28704

When: Friday, March 8, 2019, 9:30 to 4:30

Cost: $55 with Saturday and/or Sunday conference registration, $70 without.

Register here.

Here are more details about what we hope to cover during the day:

  • Defining your Market: Are you growing for yourself or for others? When and how much do you need to harvest? Learn about yields of common crops and begin to create a growing plan.
  • Season Extension: From transplants and row cover in the spring, to hoop houses in the winter, learn to keep crops alive through the seasons. Calculate the last worthwhile planting date in your area, and choose a suitable combination of warm weather crops, cool weather crops, storage crops and cold-hardy crops appropriate for your scale.
  • Temperature Resilience: Discover tips to deal with extreme hot and cold temperature ranges including getting seeds germinated, identifying crops that do well in both extremes, and the importance of crop diversification. Climate change necessitates adaptive growing practices. We will incorporate soil building and water management, as well as the importance of seed saving and variety trials.
  • Crop Rotation: Keep roots in the ground at all times! Learn the art of crop rotation using planting calendars, observation, and garden planning. Discover relay planting, cover cropping, isolation distances, plants to attract pollinators, as well as tricks for fitting minor crops into available spaces.

On Saturday and Sunday at 9.00-10.30 am I will be teaching Sustainable Farming Practices, with a primary audience of beginner farmers. (Everyone is welcome!).

 

 

 

 

 

 

 

 

An intro to year-round vegetable production; crop planning; record-keeping; rotations; cover crops; compost; and mulch. Also direct sowing and transplanting; crop spacing; succession scheduling for continuous harvests; efficient production strategies; season extension; pests, diseases and weeds; determining crop maturity and harvest methods.

The Organic Growers School Spring Conference is for farmers, gardeners, homesteaders, and sustainability seekers.The Spring Conference offers practical, region-specific workshops on farming, gardening, permaculture, urban growing, and rural living and includes a trade show, a seed exchange,special guest speakers, and a Saturday evening social. More than 150 classes—both 90-minute sessions and half-day workshops—are offered on Saturday and Sunday in 17 learning tracks:

1.Community Food

2.Cooking

3.Earth Skills

4.Farmers: Beginning

5.Farmers: Experienced

6.Gardening

7.Herbs

8.Homesteading

9.Livestock

10.Mushrooms

11.Permaculture

12.Pollinators

13.Poultry

14.Soils

15.Sustainable Forestry

16.Sustainable Living

17.Thinking Big

“The Spring Conference features a trade show on Saturday and Sunday that showcases a wide array of exhibitors and products from local farms, gardening suppliers, and cottage industries that specialize in organic products and resources. Also featured on Saturday and Sunday is the annual Seed and Plant Exchange booth which offers the opportunity to preserve genetic diversity and protect regionally adapted varieties. Attendees may bring excess seeds and small plants to share, barter, or trade.For 25 years, the Spring Conference has allowed OGS to reinforce Western NC’s role as a regional leader in sustainable food and farming. Attendees come from 18 states and Canada and have described the event as the kick-start to the growing season. The event has grown exponentially—from a small gathering of 100 growing enthusiasts in 1993 to a regionally recognized conference drawing over 2,500 attendees, exhibitors and speakers.“The 25th Anniversary of the OGS Spring Conference is really a celebration of our regional wisdom and commitment to land stewardship, sustainable food systems, and local farming,”says OGS Executive Director, Lee Warren.“The conference is a gathering place, a source of inspiration, and a reminder of the richness of our community,”

The 25th annual Virginia Festival of the Book will take place Wednesday, March 20 through Sunday, March 24, 2019 in venues across Charlottesville and Albemarle County, Virginia. For more, click Virginia Festival of the Book 2019 Schedule.

I have two talks:

“Pam Dawling (The Year-Round Hoophouse) and co-authors Claudia Kousoulas and Ellen Letourneau (Bread & Beauty) discuss their personal approaches to preserving, cultivating, and enjoying land responsibly in the Mid-Atlantic region. Book sales and signing will follow. FREE to attend and open to the public.”

Tanya Denckla-Cobb

The panel will be moderated by local author Tanya Denckla-Cobb

 

Claudia Kousoulas

 

 

Ellen LeTourneau

 

Year-Round Hoophouse Vegetables slide show, and the decision between transplanting and direct sowing

I’ve feeding in a flurry of slideshows I’ve been presenting at conferences this winter. You’ll notice a lot of them have a hoophouse theme, although not all. Here’s one from the four hour course I gave at the Virginia Association for Biological Farming conference.

To view the slideshow full screen, click the diagonal arrow icon. You can then hop, skip and jump through it, choosing the bits you are interested in.

My other main topic this week is choosing when to transplant and when to direct sow. I am a big fan of transplanting, so I’ll start with that.

Watermelon transplants in a Winstrip plug flat. Watermelons give earlier harvests from transplants, and plants in plug flats transplant easier than from open flats.
Photo Pam Dawling

Advantages of transplanting:

  • You can start earlier in the year than you can outside, and so get earlier harvests
  • By starting seed in more ideal conditions in a greenhouse, (or on a kitchen windowsill), you’ll get better growth, more satisfaction!
  • It is easier to care for new seedlings indoors – major weather events stay outdoors!
  • You can fit more crops into each bed throughout the season, because each crop is occupying the bed for less time than if direct-sown.
  • Transplanting. can help you grow more successions of summer crops, as each one needs less time in the garden or field. This helps you always have good quality fresh produce for harvest.
  • If you don’t want or need to plant more food crops, you can use those time windows for quick cover crops, such as buckwheat in warm weather, mustards in cold weather.
  • You will save on seed costs, because you’ll be sowing and spotting or potting up, then transplanting, not sowing long rows and thinning most of the plants out.
  • Using transplants fits (better than direct sowing does) with using plastic (or paper) mulches, which can help with weed control and soil warming (or cooling).
  • Using transplants fits well with no-till cover crops. Mow or roll-and-crimp the cover crops, transplant into it, and the dead mulch keeps the weeds away for 6-8 weeks in our climate, longer in cooler and drier climates.
  • Transplanting works well for crops where you want several varieties, such as tomatoes and peppers.

    Amy’s Apricot tomato from Southern Exposure Seed Exchange. Transplanting works well for crops where you want a few plants each of several varieties.
    Photo Pam Dawling
  • You have more flexibility if the weather turns bad, for example if spring is cold and/or wet. You can delay transplanting. Your plants still grow, provided the roots have enough space. If you know they won’t, you can pot them up to provide more root space.
  • At transplanting time, you can select the sturdiest plants, and compost the rest, meaning you have the best chance of good yields.

Disadvantages of transplanting:

  • If you extend the season and start earlier, you will have more work. . .
  • You’ll need to spend extra time caring for the starts indoors, as they won’t get water if you don’t provide it.
  • Transplant shock can delay harvest, so be sure to learn and practice good techniques
  • More attention is needed to watering new plants after transplanting, (compared to direct seedling) as some root damage is almost inevitable. (Plug flats and soil blocks minimize root damage)
  • If you don’t have a good irrigation system or water supply, growing many transplants will be a challenge.
  • Likewise you do need a good greenhouse set-up to grow many transplants.

Advantages of direct seeding:

  • See the disadvantages of transplanting.
  • Direct seeding is less work than transplanting. Put the seed in the ground, water as needed and stand back!
  • You do not need a greenhouse or special transplanting equipment
  • Compared to buying starts, direct sowing has lower costs
  • Direct sown crops have better drought tolerance – the roots grow without damage
  • Some crops just don’t transplant easily: melons which have fragile stems and roots for instance, or carrots which get distorted roots if transplanted.
  • Some crops have millions of plants and you couldn’t possibly transplant enough:  (Carrots)

    Carrot rows thinned to 1 inch. Carrots are too numerous to transplant and transplanting stunts and distorts the roots, so they are best direct sown.
    Photo Kathryn Simmons

Disadvantages of direct sowing:

  • See the advantages of transplanting.
  • Direct sowing uses more seed than transplanting.
  • Direct sowing requires more time thinning
  • Direct sown crops occupy the land longer than the same crop transplanted.
  • Some direct-sown crops may be harder to get started in cold (or hot) conditions.

There are probably others, do let me know!

For those wanting to sow large-seeded crops through plastic mulch, see below for how we planted beans.

To sow beans through biodegradable plastic mulch, we made this dibble from bamboo, dowels, a culled hammock stretcher bar and plumbing strapping. Photo Nina Gentle
Using the bean dibble to punch holes through the plastic mulch (the soil is holding down the edges of the mulch).
Photo Brittany Lewis
Sowing beans through holes we made in the biodegradable plastic mulch.
Photo Nina Gentle
Beans growing on biodegradable plastic mulch.
Photo Nina Gentle

Preparing for spring, sowing seeds, Crop Planning slide show

 

Here’s my updated Crop Planning slideshow, which I presented last weekend at the Virginia Association for Biological Farming Conference. To view it full screen, click the diagonal arrow in the lower right.

I will upload my other presentations bit by bit. January and early February are choc-a-bloc with conferences and slideshows, so there will be plenty to see in the next couple of months!

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Seed flats in the greenhouse in early spring.
Photo Kathryn Simmons

Spring starts in January in Virginia! On January 17 we make our first sowings in the greenhouse. We sow some early cabbage, the first lettuce, and some scallions. The week after that we sow our hoophouse tomatoes! Ah! Signs of spring! Even if we did manufacture them, so to speak!

Our germinator cabinet is made from a broken fridge, warmed by an incandescent light-bulb. We’ve got maybe one more year before we run out of incandescent light-bulbs. Then we’ll have to get a different form of heating. But we’re shelving that problem for now. We check twice a day to make sure the light-bulb is still working and the temperature in the germination chamber is still OK.

By the end of February, we’ll have sown tomatoes and peppers for growing in our hoophouse, and spinach, kale, collards, cabbage, lettuce, scallions, broccoli and senposai for planting outdoors.

When the cabbages emerge, we’ll need to make space for the flat in the greenhouse near the window. When the hoophouse tomatoes have germinated, they will go in a plastic tent on a seed heating mat by the greenhouse windows. We have the 48″ x 20″ size mat, and we extend the plastic tent and graduate the older seedlings off the mat, but still under the tent for extra protection.

Screening compost to fill our greenhouse beds in September.
Photo Wren Vile

Our system for seed compost is to screen a big pile of our homemade compost in September, and fill the cinder-block beds in the greenhouse. Then we pop lettuce transplants at 10″ spacing into the beds. Those lettuces give us salad from November to February. As we need space in the greenhouse, we pull the lettuce. We can then scoop out the compost to fill the flats for seedlings. This system works well time-wise –we benefit from this lettuce supply in the winter. It also works well in providing us with a large quantity of mellow screened compost for seed flats, indoors and not frozen. The soil organisms have had time to colonize the compost, so it is full of life.

Walking the gangplank to fill greenhouse beds with compost in September. Photo Wren Vile

As the seedlings grow, we spot them out into bigger flats, with about 2.5″ between plants. My favorite tool for this job is a butter knife! For lettuce we use 3″ deep flats, but for most crops we use 4″ deep flats, so the roots have plenty of space. We use a dibble board to make the evenly spaced holes in the compost in the bigger flats, to move the tiny seedlings into. It’s a piece of plywood with fat dowel pegs glued into holes at the right spacing, 40 in a 12″ x 24″ flat. On the other side of the board are two small wood handles to make it easy to use.

A flat of scallions to transplant in April.
Photo Pam Dawling

There is a great website on Vegetable Transplant Production from the University of Florida Vegetable horticulture Program. It has a collection of excellent articles developed by Charles Vavrina in the late nineties. Plants still grow the same way! Check out the site for lots of useful tips about growing and using transplants. This is a good time of year to make plans to do something in a different way, to avoid repeating last year’s less successful episodes!

You can see our Twin Oaks Month-by-month Garden Task List here on my website.

 

Alliums for January: sow scallions, cipollini, shallots

Clumps of scallion transplants in a plug flat, ready to transplant.
Photo Pam Dawling

Plant scallions, shallots, cipollini mini-onions, small potato onions

In January, one of the first crops we sow is scallions for transplant. We sow in 200-cell plug flats, on January 17, aiming to get 4-6 seeds per cell. It takes 4 gm of seed for 200 cells. We transplant these clumps on March 21, with 3″ (7 cm) space between plugs. We need about 50 row feet (15 m) This grows us scallions already in bunches, and makes excellent use of the space. We make a second sowing of the same size on February 17 and transplant April 14. We also grow scallions in the hoophouse in winter.

French Red Shallot bulbs. Photo Raddysh Acorn

 Plant shallot bulbs January-February, if you haven’t done so before the winter.

Between late January and mid-February, sow shallot seeds. Transplant in late March. Shallots from seed will be ready for harvest 7/4-7/30, about a month later than harvests from replanted bulbs.

Cipollini, Mini-onions, Pickling Onions

Like bulb onions and scallions, cipollini are a biennial crop grown as an annual (A. cepa var. cepa). They are small bulb onions used whole for kebabs, pickles, casseroles, and stews. Depending on your latitude and the variety’s adaptation, these will provide bulbs from the size of large cherries to ping-pong balls. They tend to dry down nicely and store well. White varieties get sunburn here. Red Marble is good, stores well. Purplette doesn’t store well.

Mini-onions are viewed as a gourmet item, so the prices you can get may justify giving them greenhouse bench space, or even growing space in a hoophouse. We can grow these outdoors from seed sown 1/17-1/25, transplanting 3/10-3/21, leading to harvest 7/1-7/17.

Red Marble cipollini.
Photo Fedco Seeds

Small potato onions

In late January, plant small potato onions (smaller than 1.5″/4 cm) late January as soon as the ground can be worked. Or early February, if January is not possible. See Alliums for December for planting medium-sized bulbs, Alliums for September for information on planting the large ones. In order to make January planting possible, we prepare the bed for the small potato onions in the late fall and cover it with mulch for the winter. In late January or early February, we remove the mulch, make 4 deep furrows, plant the small onions (<1½”, 4 cm) on 4″ (10 cm) centers, cover with ½”-1″ (1-3 cm) soil, tamp down, and replace 4″-8″ (10-20 cm) of mulch. Label and write down how much seed was used. Eat any leftovers or give them to a friend. For 360′ (111 m) at 4″ (10 cm), we need 1080 bulbs plus 20% spare. (Approx 1300 bulbs). 425 bulbs = 18-20lbs (8-9 kg), 1lb (500 gm) =20-33 bulbs.

Harvesting and Eating

Eat onions and garlic from storage, including bulbils from Egyptian onions if you stored those.

You can enjoy eating Perennial leeks as leeks, September to February. See Alliums for December

If still green and visible, you can eat leaves of Egyptian onions and perennial leeks, September to April.

This is the time to enjoy winter leeks. We try to grow enough to supply 1 bed (720 leeks) each month, December to February

Other Allium Tasks

How to harvest and trim leeks.

Use a sturdy digging fork to harvest leeks.
Photo Pam Dawling

Be sure to get the prongs/times of the fork downwards into the soil, not at an angle that will stab the leek. Step on the fork and go deep enough to dislodge the leek when you lever back on the fork.

Trim the leek roots off with a big knife.
Photo Pam Dawling

After removing the roots, hold the leek upside down and slash diagonally at the leaves. This will remove the damaged parts of the tougher outer leaves and leave the tender inner leaves to eat.

A trimmed leek showing how the inner leaves are left longer than the outer ones.
Photo Pam Dawling

If you haven’t done it already, free trapped garlic shoots. Look for garlic shoots at whatever spacing you used.

Young garlic shoots which emerged through the mulch on their own.
Photo Pam Dawling
A trapped garlic shoot that was freed with human intervention.
Photo Pam Dawling

If you don’t see a garlic shoot where there should be one, part the mulch just enough to let the pale shoot see the light. Don’t leave any soil bare, it only leads to weeds!

Unusual Alliums List. (There are others)

While you are perusing seed catalogs, look out for these less common alliums, and consider if they have a place in your garden. The Clove Garden has lots of info on all types of onion. The Backyard Larder: Ali’s Alliums is also a good read.

  1. Pearl onions (Allium ampeloprasum sectivum), also known as button or baby onions in the UK, or creamers in the US, are a close relative of leeks, with thin skins and a mild, sweet flavor. They grow up to 1′ (2.5 cm) in diameter. They are especially popular in the Netherlands and Germany. Unlike bulb onions, they do not have layers of storage leaves but only a single storage leaf, like the non-layered cloves of garlic. The onions are ready to harvest 90 days from sowing. They are mostly used for pickling. Most onions grown for pickling today are simply small crowded bulb onions, with layers. Also see the Useful Temperate Plants Site  and How to grow Pearl Onions by Jenny Harrington
  2. Perennial Rakkyo (aka as true pearl onions, Japanese scallions, Vietnamese leeks) are Allium Chinense. These small onion bulbs are generally pickled.
  3. Canada onion (aka Wild onion) (Allium canadense) is a perennial sounding very like what we call onion grass or wild garlic in Virginia, although that is Allium vineale (crow garlic). The leaves of onion grass are hollow and round, while those of Canada onion are more flat and ‘solid’.
  4. Kurrat ( kurrat), is a Middle-Eastern cultivated leek, used mainly for the greens, which may be cut from the plant repeatedly.
  5. Field garlic Allium oleraceum is native to most of Europe, where it is a wild perennial, growing tall leaves (the part that is used).
  6. Ramsons Allium ursinum, buckrams, wild garlic, broad-leaved garlic, wood garlic, bear leek, or bear’s garlic, common in Europe. Looks like Ramps, (Allium tricoccum) but is not the same. The broad flat leaves are the part used.
  7. Japanese bunching onion and Welsh onion (native to Siberia or China, not Wales) are Allium fistulosum. They are sometimes used as scallions, as are some A. cepa. Young plants of A. fistulosum and A. cepa look very similar, but may be distinguished by their leaves, which are circular in cross-section in A. fistulosum rather than flattened on one side.  A. fistulosum has hollow leaves (fistulosum means “hollow”), scapes and does not develop bulbs – the leaves are the part which is eaten.

Back-up plans for winter hoophouse crops

Lettuce “filler” transplants to fill gaps.
Photo Pam Dawling

Because crops grow slowly in cold weather, if something goes wrong at the beginning of the winter, or in the fall, the consequences can cast a long shadow. It is not easy to make up for lost time. In spring, the weather is getting warmer, the daylight is lengthening, and you may have noticed that later sowings can catch up with ones a week or two earlier, allowing for a second chance. In the fall, the rate of growth is moving in the opposite direction, and later sowings will stand no chance of catching up. Even worse, they may get “trapped” like Persephone in the Underworld during the dark Persephone Days. But don’t despair – there are things you can do ahead of time to be prepared for plans going awry, and there are even a few things you can do instead of your original plan, to ensure you get some crops to harvest.

Transplant seedlings under insect netting outdoors.
Photo Pam Dawling

Starting outdoors in September

We sow a lot of our winter crops outdoors in September, and transplant them into the hoophouse in October. This gives us an extra few weeks to prepare the hoophouse beds, and gives the seeds the cooler outdoor conditions to germinate in. We have three sowing dates.

On September 15, we sow 10 varieties of hardy leaf lettuce and romaines; pak choy, Chinese cabbage, Yukina Savoy, Tokyo Bekana, Maruba Santoh and chard

On September 24, we sow another 10 varieties of lettuce; Red and White Russian kales, Senposai, more Yukina Savoy, mizuna and arugula, and we resow anything that didn’t do well in the 9/15 sowing

On September 30, we resow anything that didn’t do well in the 9/24 sowing, or substitutes.

Emergency back-up seedlings for the hoophouse.
Photo Pam Dawling

This year, we had poor germination of a lot of the 9/15 sowings and too many of the 9/24 sowings. As a back-up for the back-up plans we sowed some crops in Winstrip trays, and spotted lettuce in open flats, which we kept inside the hoophouse. By that point, conditions in the hoophouse were more crop-friendly than outdoors. We did need some of these, and the rest we harvested for salad mixes right out of the flats! We were short of salad items because of the late establishment of the plants, so every plant was a help!

A flat of lettuce transplants in the path in the hoophouse.
Photo Pam Dawling

Our goal is to keep the space filled with useful crops.

Success with this goal relies on a cluster of strategies

  1. The fall transplant program I describe above.
  2. Follow-on crops: A sequence of different crops occupying the same space over time. It’s important to know when crops will bolt, and how to plant sensible quantities
  3. Filler crops: As well as scheduled plantings, in October we sow a few short rows of spinach, lettuce, Senposai, Yukina Savoy, Maruba Santoh, Tokyo Bekana to transplant into gaps as soon as they occur. We simply dig them up, replant where needed and water well. Bare-root transplants are much easier than many fear. They save time and money, compared to growing starts in flats, and save on greenhouse space. They are very sturdy plants, as they have the full depth of soil to develop big roots. Little extra care is needed, as they are less prone to drying out than seedlings in flats. Alternatively you could keep some plug flats of these plants handy. We fill gaps with Asian greens, spinach or lettuces as appropriate, until Jan 25. From Jan 25 to Feb 20 we fill all gaps everywhere with spinach From Feb 20, we only fill gaps on the outer thirds of the beds, leaving centers free for tomatoes, etc.

    Filler brassica transplants in our hoophouse in November.
    Photo Pam Dawling
  4. Interplanting: After 2/20, we harvest the winter crops from the center rows first, plant the new early summer crops down the center, then harvest the outer rows bit by bit as the new crop needs the space or the light. This overlap allows the new crops to take over gradually. Our winter and spring crops end in April
  5. Fast Catch Crops. Some cool-weather crops mature in 60 days or less. Mostly these are greens and fast-growing root crops. Useful if a crop fails, or you have a small empty space. Details on some of these follow the list.
  • Ready in 30–35 days in fall, longer in winter: arugula, many Asian greens (Chinese Napa cabbage, Komatsuna, Maruba Santoh, mizuna, pak choy,.Senposai, tatsoi, Tokyo Bekana and Yukina Savoy), brassica salad mixes, chard, kale, radishes, salad greens (lettuce, endives, chicories) spinach and winter purslane. Peashoots in late winter or spring.
  • Ready in 35–45 days in fall: chervil, corn salad, land cress, parsley and sorrel.
  • Ready in 60 days in fall: beets, small fast cabbage, collards, kohlrabi and turnips.

 Asian Greens

Asian greens are better able to germinate in hot weather than lettuce, and are faster growing than lettuce. Transplant 2-3 weeks after fall sowing, or direct sow.

Asian greens are nutritious as well as tasty – flavors vary from mild to peppery – read the catalog descriptions before growing lots. Colors cover the spectrum: chartreuse, bright green, dark green and purple. A diversity of crops without a diversity of growing methods!

Brassica (Mustard) Salad Mixes

Interesting mustard mixes are sold for salad mixes. We often mix our own Brassica Salad Mix from leftover random brassica seeds. For a single cut, almost all brassicas are suitable – just avoid turnips and radishes with prickly leaves! We sow between 10/2 and 11/14 for winter harvest and from 12/4 to 2/12 for March and early April harvests. We’re zone 7, central Virginia.

Chard and Beet Greens

Green chard is hardier than the multi-colored Bright Lights. Days to maturity: 61 – 103 days, a big difference, depending when you sow. Sow 9/15, harvest 11/15 – 5/10; Sow 10/26, harvest 2/6 – 5/10.

Radishes in our hoophouse in February.
Photo Pam Dawling

Radishes

Varieties we like: Easter Egg, White Icicle, and Cherry Belle.  Sparkler got too fibrous for us, as did Cherry Belle after mid Oct. We make 6 sowings 9/6 – 1/26. Small radishes take 27–52 days to maturity, not counting days too cold to grow.

Scallions in our hoophouse in late November.
Photo Pam Dawling

Scallions

We sow 9/6 for harvest 12/1 – 3/1; 11/18 (following radishes) for harvest in early spring. This winter we are trying a sowing 10/20 also (we happened to have a space at that time, in a spot where it fitted our rotation). Evergreen Hardy White and White Lisbon scallions are hardy down to 0°F (-18°C)

Spinach

We loved Tyee and now grow Escalade, Reflect, Acadia and smooth leaf Renegade. Renegade makes good Nov/Dec growth; Acadia, Escalade yield well Jan – April; January sown Reflect does well.

  1. Succession Planting for Winter Hoophouse Crops

We do 2 sowings of chard, scallions, tatsoi and yukina savoy; 3 sowings of  mizuna, turnips and bulb onions; 4 sowings of baby lettuce mix and brassica salad mix; 5 sowings of spinach and radish. Our goal is to provide a continuous supply.

As temperatures and day-length decrease in the fall, the time to maturity lengthens – a day late in sowing can lead to a week’s delay in harvesting. As temperatures and day-length increase after the Winter Solstice, the time to maturity shortens – later sowings can almost catch up with earlier ones. To get harvests starting an equal number of days apart, vary the interval between one sowing date and the next accordingly. Here’s the most dependable method:

Making a Close-Fit Plan Using Graphs

  1. Gather sowing and harvest start and finish dates for each planting of each crop you are growing as successions.
  2. Make a graph for each crop: sowing date along the horizontal (x) axis; harvest start date along the vertical (y) axis. Mark in all your data. Join with a line. Smooth the line.
  3. From your first possible sowing date find the first harvest start date.
  4. Decide the last worthwhile harvest start date, mark that.
  5. Divide the harvest period into a whole number of equal segments, according to how often you want a new patch.
  6. Mark in the harvest start dates and see the sowing dates that match those harvest dates
Overgrown hoophouse filler greens in our hoophouse in December.
Photo Wren Vile

Working around the Persephone Days

In Indiana (in Zone 5b) Ben Hartman (The Lean Farm) sows salad greens & spinach for winter harvests every week Sept 15–Oct 15. Baby lettuce sown before Oct 22 takes 5–6 weeks until harvest. If sown Oct 24–Nov 16, it takes 8–17 weeks to harvest. In Zone 5b, if you want baby lettuce mix before December, sow before Oct 22.

Spinach sown before Oct 11 takes 4–6 weeks to harvest. If sown from Oct 20–Nov 1, it takes 12–15 weeks. To harvest spinach before December, he sows before the middle of October.

For new year harvests he sows every week Oct 15–Nov 1. He then takes a two month break from planting (Nov-Dec). Jan 1–Jan 15 he sows both salad greens and spinach for late winter.

In Zone 7 we can harvest outdoor lettuce and spinach in December, and we have less urgency about early hoophouse sowings (and we get no winter break!).

 

 

 

 

Alliums for November: Plant garlic, sow onions in a hoophouse, eat leeks

Tadorna winter leeks in October.
Photo Pam Dawling

Cold-Tolerance of Alliums

Alliums are more cold-tolerant than most people believe. Here are my observations of killing temperatures for outdoor crops. Note that crops often survive night-time lows in the hoophouse that would have killed them outdoors.

  • 12°F (−11°C): garlic tops if fairly large, most fall or summer varieties of leeks (Lincoln,King Richard), large tops of potato onions
  • 10°F (−12°C) some leeks (American Flag aka Musselburgh and Scottish Flag, Jaune du Poiteau)
  • 5°F (−15°C): garlic tops if still small, some leeks (Bulgarian Giant, Laura, Tadorna, Bandit), some bulb onions, potato onions and other multiplier onions
  • 0°F (−18°C): chives, garlic, a few leeks (Alaska, Durabel); some bulb onions, yellowpotato onions, some onion scallions (Evergreen Hardy White, White Lisbon), Walla Walla onions sown in late summer (with rowcover for winter)

Planting Garlic

Planting garlic.
Photo Brittany Lewis

You can see my garlic slideshow for more info. I was surprised to find I haven’t written much in my blog about planting garlic, so here goes! See the alliums chapter in Sustainable Market Farming for more on types, varieties, and garlic genetics. The information here comes form that chapter.

When to Plant Garlic

Plant when the soil temperature at 4″ (10 cm) deep is 50°F (10°C) at 9 am. If the fall is unusually warm, wait a week. Instructions from Texas A&M say less than 85°F (29°C) at 2″ (5 cm) deep. We plant in early November. In New Hampshire, mid-October is the time. The guideline for areas with cold winters is 2-3 weeks after the first frost but before the ground freezes solid for the winter. In Michigan, planting time is 6 weeks prior to the ground freezing, giving enough time for root growth only, to avoid freezing the leaves. In California, garlic can be planted in January or February.

Both hardneck and softneck garlic do best when planted in the fall, though softneck garlic may also be planted in the very early spring if you have to (with reduced yields). If you miss the window for fall planting, ensure that your seed garlic gets 40 days at or below 40°F (4.5°C) in storage before spring planting, or the lack of vernalization will mean the bulbs will not differentiate (divide into separate cloves).

Garlic shoots emerging from the mulch a few weeks after November planting. Photo Twin Oaks Community

Garlic roots will grow whenever the ground is not frozen, and the tops will grow whenever the temperature is above 40°F (4.5°C). In colder areas the goal is to get the garlic to grow roots before the big freeze-up arrives, but not to make top growth until after the worst of the weather. In warmer areas, the goal is to get enough top growth in fall to get off to a roaring start in the spring, but not so much top growth that the leaves cannot endure the winter. If garlic gets frozen back to the ground in the winter, it can regrow and be fine. If it dies back twice in the winter, the yield will be lower than it might have been if you had been luckier with the weather. When properly planted, it can withstand winter lows of –30°F (–35°C). If planted too early, too much tender top growth happens before winter. If planted too late, there will be inadequate root growth before the winter, and a lower survival rate as well as smaller bulbs.

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.

Popping garlic cloves in preparation for planting
Photo  Southern Exposure Seed Exchange

Popping Garlic Cloves for Planting

The garlic for planting should be taken apart into separate cloves 0–7 days before planting. We are doing this on November 7, along with our crop review meeting when the crew meets to make notes on the past season. This task is a good group activity. Twist off the outer skins and pull the bulb apart, trying not to break the basal plate of the cloves (the part the roots grow from), as that makes them unusable for planting. With hardneck garlic, the remainder of the stem acts as a handy lever for separating the cloves. We sort as we go, putting good size cloves in big buckets, damaged cloves in kitchen buckets, tiny cloves in tiny buckets and outer skins and reject cloves in compost buckets. The tiny cloves get planted for garlic scallions. Don’t worry if some skin comes off the cloves — they will still grow successfully. Cloves for planting should be from large (but not giant) bulbs and be in good condition.

Click the link to read about hot water treatment for seed garlic at WeeBee Farms. 

Pre-plant Seed Garlic Treatments

Many of us do nothing special with the cloves before planting, but if you have pest and disease problems, use pre-plant soaking treatments, usually done the night before planting. Some growers find they get better yields from treated cloves even if no problem was obvious.

To eradicate stem and bulb (bloat) nematode (Ditylenchus dipsaci), soak the separated cloves for thirty minutes in 100°F (37.7°C) water containing 0.1% surfactant (soap). Or soak for twenty minutes in the same strength solution at 120°F (48.5°C), then cool in plain water for 10-20 minutes.

Allow to dry for 2 hours at 100°F (37.7°C) or plant immediately. Anytime your garlic grows poorly and you can’t tell why, send a sample with the soil it’s growing in to your Extension Service to be tested for nematodes. Mites can eat the skins of the cloves, survive the winter and multiply all spring long, seriously damaging or even killing your crop. To kill mites (which hide between the wrappers) before planting, separate the bulbs into cloves and soak them overnight (up to 16 hours) in water.

Possible additions to the water include one heaping tablespoon of baking soda and one tablespoon of liquid seaweed per gallon (around 8 ml baking soda and 4 ml liquid seaweed per liter). Just before planting, drain the cloves and cover them in rubbing alcohol for three to five minutes, long enough for the alcohol to penetrate the clove covers and kill any mites inside. Then plant immediately. The long soaking will loosen the clove skins so that the alcohol can penetrate. Mite-infested garlic soaked like this does much better than unsoaked infested garlic. The solution used to kill mites can also be used to kill various fungal infections. The cloves need only fifteen to thirty minutes soaking.

In trials comparing treated and untreated cloves, treated cloves were larger and healthier than untreated ones. Fusarium levels can be kept down by adding wood ashes when planting and then possibly dusting the beds with more ashes over the winter (use moderation — don’t add so much that you make the soil alkaline). Or you could soak the cloves in a 10% bleach solution, then roll them in wood ash (wear gloves for handling ashy cloves). The wood ash soaks up the dampness of the bleach and provides a source of potassium. This information came from the Garlic Seed Foundation. Join GSF to find out all the details!

Other November Allium Planting

Plant shallot bulbs before the end of November and medium-sized potato onions (1.5″ – 2″, 4-5 cm) at the end of November or early December in zone 7. Finish dividing and replanting perennial leeks and Egyptian walking onions this month

Young onion plant in March.
Photo Kathryn Simmons

Special Allium Topic for November: Sow Bulbing Onions in the Hoophouse

We developed a system of growing onion starts in our hoophouse over the winter and transplanting them bare-root outdoors in very early March. I wrote about choosing onion varieties for your latitude last month. There I explained that to grow big onions we need to have large transplants on March 1, so we can have big vegetative plants before bulbing is triggered by the daylength.

The method involves making two sowings of bulbing onions, each enough for the whole planting. This provides insurance in case one date turns out better than the other. Then we follow this up with a partial third sowing to make up numbers of any varieties that didn’t germinate well. We make our first sowing November 10, our second November 20, and a third on December 5 as a back-up in case of problems. Our formula is: divide the number of onion plants wanted by 20, to give minimum length of row to sow, in feet. And sow this amount twice, 10 days apart. The onions will be planted out at 4″ (10 cm) apart. We add 20% to provide some slack. For a final row of 100′ (30.5 m), we’d need 100′ × 3 per foot × 1.2 (adding 20%) plants. 360 plants. We sow 3 seeds per inch (approx. 1 cm apart), 36 per foot (30 cm). At this sowing rate, we need 120″, or 10′ (3 m).

See The Year-Round Hoophouse for more on growing onions this way. If we find ourselves with extra onion plants in March, we usually re-categorize them as scallions. But we have also transplanted them in early March in a single row along the south edge of hoophouse beds, for an early crop. We got good onions but they dwarfed the pepper plants behind them. Maybe planting them on the north side of the bed is better?

Trimming roots from a leek in December.
Photo Pam Dawling

Storing Leeks

I wrote about how to dig up leeks last month. In zone 7 we leave our leeks in the ground till we need them, being sure to harvest the less hardy Lincoln and King Richard first. We use a walk-in cooler for short term storage (up to a week) and keep the root ends in water. Leeks are best stored at 33°F (0.5°C) and 65% relative humidity. In colder zones, leeks can be harvested and stored in a root cellar or basement. This is helpful in areas where the ground freezes solid for weeks on end. You can store leeks with the roots packed in soil, shoulder to shoulder in a crate or box in a root cellar, where they will keep for six weeks. They can be stored in plastic bags for two to three months at the right temperature, or frozen. Another possibility is to leave them in the garden, mulched with a foot (30 cm) of straw or hay as well as rowcover, if temperatures are below 10°F (–12°C). Our winter temperatures fluctuate a lot, so covering in-ground crops with mulch doesn’t work well for us.