Winter-Kill Temperatures of Cold-Hardy Vegetables 2018

Here’s the long version of one of the slideshows I presented on January 13 at the Future Harvest CASA conference. Since I got home, I updated my Winter-Kill Temperatures list, which appears in the slideshow. Compared to my list for 2016, there are a few differences, nothing major. We had some extremely cold weather, as I reported last week with some sorry pictures of lettuces. Now I have some photos of the outdoor crops too. The Vates kale had mixed survival, the rowcovered Reflect and Avon spinach are damaged but OK, the Tadorna leeks are battered but hanging in there (so are we!).

Vates kale which survived temperatures of -8F and -9F outdoors, uncovered.
Photo Pam Dawling

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

For several years I have been keeping records of how well our crops do in the colder season. I note each increasingly cold minimum temperature and when the various crops die of cold, to fine tune our planting for next year. We had some extremely cold temperatures of -8°F and -9°F (-22°C and -23°C) in early January 2018. We are in zone 7a, with an average annual minimum temperature of 0-5°F (-18°C to -15°C).

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, micro-climates and rain levels may lead you to use different temperatures in your crop planning.

Hoophouse Notes

Our double-skin 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 and the plants recover in the warmer daytime conditions (it seems to be the night+day average temperature that counts).

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

For example, salad greens in a hoophouse can survive nights with outdoor lows of 14°F (-10°C) without inner rowcover. 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.

Lettuce hardy enough for a solar heated winter 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, 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.

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.

Spinach under rowcover, with our hoophouse in the background – crop protection pays!
Photo Pam Dawling

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 15F), 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).

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, Senposai leaves (the core of the plant may survive 10°F/-12°C), some turnips (Purple Top).

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), large leaves of savoyed spinach (more hardy than flat 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.

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).

Tadorna leeks, struggling but not dead, after -9F.
Photo Pam Dawling

0°F (-18°C): Chives, some collards (Blue Max, Winner), corn salad (mache), garlic, horseradish, Jerusalem artichokes, 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, Tyee). 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

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

Reflect spinach in the open got damaged but not killed at -9F.
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

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

A cover crop of winter wheat untroubled by -9F.
Photo Pam Dawling

Year Round Vegetable Production, speaking events

Here’s my newest slide show, Year Round Vegetable Production, which I presented at the Field School in Johnstown, TN on December 7.  To view full screen, click the diagonal arrows at the bottom right, and to move to the next slide, click the triangle arrow pointing right.

The Field School is a Beginning Farmer program, under the Appalachian RC&D Council. The Field School organizes a monthly series of workshops (November 2017 through August 2018) that provides an overview of small-scale farming in East Tennessee’s mountains and valleys, taught by 20+ farmers and agricultural professionals. It is arranged by the Appalachian RC&D Council, Green Earth Connection, and many area partners with major support from USDA.

As well as my double presentation on Thursday evening, I attended a Q and A brunch on Friday morning and got the chance to meet the new (ish) farmers individually. It was a pleasure to meet such enthusiastic dedicated growers.

My other presentation on Thursday 12/7 was Crop Planning, which you can view by clicking the link.

The school session 2017-18 is already full even though they have expanded to have two tracks (Produce or Small Livestock) in this their third year. Go to their website if you are local and want to be on their waiting list if spots open up. They also sell tickets to the public for some of their workshops.

Beginning farmer training is available in most states, loosely under the USDA, but without a central organization. Do a web search for your state and “beginning farmer training” if you are looking for something like this. Or check out this list on

I have been firming up several speaking events in the new year. Here some info on some of those (click the Events tab  or the individual event links for for more details):

The Chesapeake Alliance for Sustainable Agriculture Future Harvest Conference January 11-13, 2018 at College Park, MD.

Ira Wallace (Southern Exposure Seed Exchange), Gabe Brown, Michael Twitty and Craig Beyrouty are giving the meal time addresses.

On Saturday January 13 11.30am -12.30pm I’m presenting

Cold-Hardy Winter Vegetables Why farm in winter? Information includes tables of cold-hardiness; details of four ranges of cold-hardy crops; overwintering crops for spring harvests; scheduling; weather prediction and protection; hoophouse growing; and vegetable storage.

I am also participating with other speakers in a new format Lightning Session Round, 2.15-3.30pm on Saturday, where we each get 10 minutes to tell the audience the top 5 things we want them to know about a certain topic. I’m speaking on Six Steps to Using Graphs to Plan Succession Crops for Continuous Harvests

I will be signing books at the Southern Exposure Seed Exchange booth at points during the conference.

February 7-10, 2018 Pennsylvania Association for Sustainable Agriculture, Farming for the Future Conference, State College, PA  I’ll be presenting three workshops:

Storage Vegetables for Off-Season Sales Friday 12.50 – 2.10 pm

Grow crops you can sell during the winter, while allowing yourself some down-time and reprieve from outdoor work. Choose suitable crops, schedules and storage conditions. Understand your weather and basic crop protection. This workshop will provide tables of cold-hardiness and details of four ranges of cold-hardy crops (warm and cool weather crops to harvest and store before very cold weather; crops to keep alive in the ground further into winter, then store; hardy crops to store in the ground and harvest during the winter, and overwinter crops for early spring harvests before the main season). It includes tables of storage conditions needed for different vegetables and suggestions of suitable storage methods, with and without electricity.

Cover Crops for Vegetable Growers Saturday 8.30 – 9.50 am

Using cover crops to feed and improve the soil, smother weeds, and prevent soil erosion. Selecting cover crops to make use of opportunities year round: early spring, summer, fall and going into winter. Fitting cover crops into the schedule of vegetable production while maintaining a healthy crop rotation.

Fall and Winter Hoophouses Saturday Feb 10 12.50-2.10pm

How to grow varied and plentiful winter greens for cooking and salads; turnips, radishes and scallions. How to get continuous harvests and maximize use of this valuable space, including transplanting indoors from outdoors in the fall. The workshop includes tips to help minimize unhealthy levels of nitrates in cold weather with short days. Late winter uses can include growing bare-root transplants for planting outdoors in spring.

There will be handouts for each workshop and book signing

March 9-11 2018, Organic Growers School Spring Conference at UNC-Asheville, Asheville, NC. I’ll be presenting three workshops:

For the Gardener track: Growing Sweet Potatoes from Start to Finish

At this workshop you will learn how to grow your own sweet potato slips; plant them, grow healthy crops and harvest good yields, selecting suitable roots for growing next year’s slips. You will also learn how to cure and store roots for top quality and minimal losses. This workshop will be useful to beginners and experienced growers alike.

For the New Farmer Track: Cover Crops for Vegetable Growers

Using cover crops to feed and improve the soil, smother weeds, and prevent soil erosion. Selecting cover crops to make use of opportunities year round: early spring, summer, fall and going into winter. Fitting cover crops into the schedule of vegetable production while maintaining a healthy crop rotation.

Sustainable Farming Practices 

An introduction to year round vegetable production; crop planning and record-keeping; feeding the soil using crop rotations, cover crops, compost making and organic mulches; production tips on direct sowing and transplanting, crop spacing, succession crop scheduling to ensure continuous harvests, efficient production strategies, season extension, dealing with pests, diseases and weeds; determining crop maturity and harvest methods.

April 12, 2018, 9am to noon,

Louisa Master Gardener Group Tour of Twin Oaks Gardens

Cold nights, Cool season hoophouse crops, CASA conference

Ginkgo Golden Puddle Day
November 10 2017.
Photo Pam Dawling

We had a few 24F nights and the ginkgo trees responded by instantly dropping all their leaves. A beautiful sight.

At the Carolina Farm Stewardship Association Sustainable Agriculture Conference I gave a presentation called Sequential Planting of Cool Season Crops in High Tunnels as part of the Friday morning High Tunnel Crop Production Intensive workshop. It’s a new workshop I prepared especially for the CFSA. I usually call the structures hoophouses rather than high tunnels, but either name is fine. It used to be said that farmers called them hoophouses and researchers and academics called them high tunnels. Nowadays there is not such a binary distinction; farmers do research and teach, researchers and academics grow crops. Here is the longer version of the slideshow, including “bonus material” I didn’t include in the 60 minute presentation. Click the diagonal arrow icon to view full screen.

On the Sunday I gave a presentation on Year-Round Hoophouse Production which was a back-to-back presentation of the Hoophouse in Spring and Summer and the Hoophouse in Fall and Winter.  You can view those slideshows by clicking the links to them on the site.

I’ve added a new event to my calendar for January. You can see all the events I plan to speak at, by clicking the Events tab at the top of the screen on my home page. This one is the Chesapeake Alliance for Sustainable Agriculture Future Harvest Conference January 11-13, 2018 at College Park, MD.

On Saturday January 13 11.30am -12.30pm I’m presenting Cold-Hardy Winter Vegetables – Why farm in winter? Information includes tables of cold-hardiness; details of four ranges of cold-hardy crops; overwintering crops for spring harvests; scheduling; weather prediction and protection; hoophouse growing; and vegetable storage.

I might also be participating with other speakers in a new format Lightning Session, where we each get 10 minutes to tell the audience the top 5 things we want them to know about a certain topic. That isn’t decided yet.

I also hope to be signing books at the Southern Exposure Seed Exchange booth at some point.

Meanwhile here on the farm it’s got colder, as I said at the beginning, and even dreary some days. We are getting our winter carrots harvested, getting ready to plant garlic, adding draft-proofing strips to our hoophouse doors, and admiring and harvesting our hoophouse salad crops.

November hoophouse lettuce bed.
Photo Wren Vile

Saving watermelon seed, rainy day reading, Heritage Harvest Festival

Scooping watermelon seed.
Photo Pam Dawling

I wrote recently about saving tomato seed, and here I’ll write about extracting watermelon seed. We grow Crimson Sweet Virginia Select, which we sell to Southern Exposure Seed Exchange. I walk through the patch with a grease pencil (china marker) in July when the melons are forming and write numbers on 40 nice-looking big melons. I’m selecting for earliness, size, disease resistance and flavor.

Selected watermelon with an identifying number.
Photo Nina Gentle

Once the melons start to ripen, I go out to the plot once a week with my trusty garden cart and a collection of clean buckets, a notebook and pen, a big knife, a large slotted spoon, a couple of damp rags, a bottle of water and a big straw hat. I start testing the numbered ones for ripeness. If they are ripe I decide if they are seed-worthy, demoting any with dead vines (not disease-resistant!) or too small. I find promising replacements for any I decide not to save seed from, and number those.

Garden cart with supplies for watermelon seed collection.
Photo Pam Dawling

When I have a good one, I cut it in half and scoop the heart out into a very clean bucket. I taste a piece (that’s the “good flavor” test). These days they all seem to taste good, but the first few years of seed selection, I had some I didn’t like much, so I didn’t save seed from those. See the first photo for the scooping task. Once the heart is scooped out, there is a layer of flesh with seeds in, which I scoop out into a moderately clean bucket. Then a layer of flesh without seeds for the food bucket.

Watermelon seed bucket and food bucket.
Photo Pam Dawling

In the blue bucket is my “dry zone” with my notebook. I write down which melons I harvested, any I discarded, any new ones I added, and how many are left to find in the coming weeks. Generally I harvest 7-10 watermelons per week, generating two buckets of fruit and two half-buckets of seeds. The watermelon seeds are fermented for four or five days, then washed – just like processing tomato seeds I wrote about last week.

Dried watermelon seeds in a paper bag.
Photo Pam Dawling

I harvest 5 or 6 times, from Late July to early September. I don’t want to be selecting for late-ripening melons so I stop harvesting seed long before the fruits are over.

My most recent blog post for Mother Earth News is about repairing garden hoses, most of which you already read about here. It’s in the DIY blog this time (most of my posts go in the Organic Gardening blog). I just heard some numbers for how various of my Mother Earth News blogposts this year are doing, and the big favorite topic is Growing Lettuce Year Round: Succession Planting for a Continuous Supply: 10,924 views! Growing Winter Lettuce: 4,620 views, is second favorite. people sure do love lettuce! Other popular topics this year have been Winter Hoop House Harvest Schedule, Using Open Flats (Seed Trays) to Grow Sturdy Seedlings EasilyHeat-Tolerant Eggplant Varieties, and Planting Leeks. 

How to harvest garlic scapes.
Photo Wren Vile

When I look to see which posts on this blog people visit most often, I see that garlic harvesting and garlic scapes are very popular, as are posts about sweet potatoes.

Sometimes I post links to my slideshows, but here’s a You Tube I’ve been meaning to tell you about. This is my presentation of Succession Planting for Continuous Vegetable Harvests at New Country Organics.

The September Growing for Market is out. The cover article, by Carolina Lees, advocating a Farmer Retreat. This is a wintertime regional gathering of farmers, with scheduled time for discussion and also for casual hanging-out. No imported speakers! The author is in Oregon, and envy-inducing photos of the beach-side retreat are included. But, what a good idea!

David Ross writes about grower relationships with wholesalers. Shawn Jadrnicek, author of The Bio-Integrated Farm: A Reveolutionary Permaculture-Based System . . .  writes about mulching and crimping techniques for no-till vegetables, including how to have weed-free cover crops, and get the right machinery to roll and crimp them. he uses a manure spreader to spread tree leaf mulch, and shows photos of a very tidy farm.

Rowan Steele writes about obtaining used silage tarps (as advocated by Jean-Martin Fortier) for covering beds to control weeds organically. Rowan writes about how to use the tarps and suggests coordinating a used silage tarp delivery for your small farm community. Contact Travis Quirk at the nonprofit Simply Agriculture Solutions Inc. in Saskatoon, Saskatchewan ([email protected]).  The tarps may be delivered for the cost of shipping. Canadian farmers are required to recycle their “grain bags”, but it’s hard for them to find a recycling facility in Canada, so the plastics are sent to the US. They are happy to be able to divert the material for a second use. Sounds great to me!

Jane Tanner writes about William’s WIldflowers, a floral design business run by two sisters, using lots of native flowers, especially perennials, for weddings and other formal occasions.

See you at the Heritage Harvest Festival on Friday September 8 (my premium workshop on growing sweet potatoes from start to finish) or Saturday (strolling around). Last time I looked there were still tickets available for my workshop ($20)

Heritage Harvest Festival

Asian Greens Slide Show, Crops in our Hoophouse

I’ve started my year of monthly posts about Asian greens with one about senposai and at the Mother Earth News Fair in Vermont this past weekend, I presented my slide show on Asian Greens, which is here for those who missed it. Click the diagonal arrow symbol to get the full screen version.

Today, back on the farm, I spent the morning in the hoophouse. I harvested 4 buckets of cucumbers from one 90′ bed of Spacemaster bush cucumbers. We harvested 2 buckets two days ago, and today they have really taken off!

Flowering cucumbers in our hoophouse May 25. Photo by Alexis Yamashita

I also harvested 3 gallons of green beans – we planted Strike, a very upright variety. We find that bush beans tend to sprawl in the hoophouse, and the varieties that do well for us outside (Provider and Bush Blue Lake, from Fedco Seeds), grow straggly inside and the beans curve. It’s probably because the shadecloth on the hoophouse is too dark for beans.

Strike beans in our hoophouse. See the big shade cloth over the hoophouse.
Photo Alexis Yamashita

The Gentry yellow squash are doing very well. I’ll harvest those tomorrow (we’re alternating cucumber and squash harvest days currently)

Gentry yellow squash in our hooophouse.
Photo Alexis Yamashita

The other crops in our hoophouse now are peppers (we’ve had a handful of green bells). two beds of tomatoes that have been struggling with aphids and sooty mold, and some Iron and Clay cowpeas as cover crops. See this sad picture of the aphids and sooty mold:

Tomato plant with aphids and sooty mold.
Photo Alexis Yamashita

Aphids excrete a sweet liquid called honeydew. In warm moist conditions this sugary substance grows a black mold on every deposit. This is called sooty mold. We have been dealing with it by jet-washing some of the tomatoes every sunny day, and we are winning. The photo above was specially chosen to demonstrate the problem – it’s not a crop to be proud of at this point! We use a brass jet-spray nozzle on a hose and wash them in the middle of the day, so the leaves can dry quickly – we don’t want any more fungal tomato diseases moving in!

Garlic scapes, upcoming events, hoophouse seed crops

Garlic Scapes
Photo courtesy of Small Farm Central

I always know when garlic growers in slightly warmer or more southern climates are starting to find scapes (the edible firm flower stems of hardneck garlic) because my posts about scapes suddenly become popular! My posts “Garlic scapes! Three weeks to bulb harvest,”  and “Garlic scapes to cheer us up” have been reread a lot recently, and Harvesting garlic is due for attention any time now. My Growing Great Garlic slideshow is here. Click the diagonal arrows to view it full screen.

And sure enough, our own scapes are ready too, even though this is a week earlier than usual.We harvest two or three times a week until there are no more. I love garlic scapes as one of the first outdoor crops of the spring, and a flavor different from leafy greens and stored roots, the staples of early spring.

Our tulip poplars are flowering now too, also early. Our average date for those is 5/1, and we’re a few days ahead of that. When I was a beekeeper it was important to be ready for the tulip poplar flowers, because that was our big nectar flow of the year, and I had to dash out to the beeyard and stack up 5 supers on each hive. I had to give up on the beekeeping because the combination of lifting heavy boxes and twisting was hurting my back too much. Oh, and those heavy boxes were full of thousands of stinging insects, but I didn’t mind that bit as much. The flowering of tulip poplars and the germination of ragweed are both phenology signs that signify that the Growing Degree Days have reached 200 (on a base of 50F) and that conditions are warm enough to sow sweet corn. Myself, I watch the young leaves on the white oaks and when they are the size of a squirrel’s ear, I decide it’s warm enough for corn.

This weekend I will be at the Mother Earth News Fair in Asheville, NC. Click the link to see the location, the workshop schedule and the list of vendors who’ll be there. I’m presenting two workshops, Growing Sweet Potatoes from Start to Finish on Saturday 5/6 at 12.30on the Yanmar Sustainable Agriculture Stage, followed by book-signing and chatting at the Mother Earth News Bookstore; and Succession Planting for Continuous Vegetable Harvests on Sunday 5/7 at the Heirloom Gardener Stage.

Of course, you’ll need to be there and  hear me speak to get the most out of it. I’m also doing short demonstrations of How to String Weave Tomatoes at booth 2800, New Society Publishers (near the Bookstore) on Saturday at 10 am, 11 am and 5 pm, and on Sunday at 10 am and 11 am. They’re half-hour time slots. My table top demo kit uses #2 pencils and pink tinsel.

At the New Society Publishers booth at the Pennsylvania Mother Earth News Fair, demonstrating how to string weave tomatoes.
Photo Ingrid Witvoet/New Society

The May issue of Growing for Market magazine is out, including my article about growing seed crops in hoophouses. I interviewed Clif Slade, founder of the 43560 Project at Virginia State University, about several creative sequences of food crops and seed crops he has grown in a high tunnel. (Collards, okra) as well as plant starts (sweet potatoes, onions). He farms in Surry County, Virginia.

Also in this GfM, Simon Huntley of Small Farm Central encourages small farmers to set aside two hours a week for a quick and efficient bit of online marketing “One Photo,
One Paragraph”. His goal is to help farmers stay in the spotlight with their products, without having to spend a great deal of time on it in the busy season.

Conor Crickmore has an article about preparing and laying out no-till permanent raised beds very precisely in a hoophouse. He uses the Quick Cut Greens Harvester to mow off over-size baby salad crops to clear the bed prior to broadforking and adding needed soil amendments.

Spencer Nietmann writes about what it really costs to start a farm. Jesse Frost discusses various types of plastic to cover hoophouses  (high tunnels), and lastly, Jane Tanner writes about native perennials for flower farms

Growing for Market, Sweet potato propagation and yields

The April issue of Growing for Market is out! For those of you growing sweet potatoes, Andrew Schwerin from NW Arkansas has written an interesting article. I’ve written about starting sweet potato slips before and I have a slideshow that includes three methods of  starting your own slips.  He and his wife Madeleine grow 1500 feet of sweet potatoes each year, a third of their growing area.

I was interested to note their reasons for growing so many sweet potatoes (apart from the obvious fact that they can sell that many). Sweet potatoes are not a big moneymaker in terms of the space occupied. Here at Twin Oaks we pondered similar issues this winter when deciding which crops to grow.  We worked down a list of 25 factors, deciding which were important to use. We chose our top handful of factors and then worked down a list of crops we might grow, awarding points (or not!) for each factor for each crop. This helped us narrow down what to focus on this year. And yes, we are growing sweet potatoes! I wrote about this in Growing for Market in February 2017.

These growers listed the following factors as their reasons to grow sweet potatoes:

  • Sweet potatoes produce well in our soil

  • They aren’t troubled by intense summer heat

  • Extensive vines will smother most weeds

  • Few pest or disease issues

  • Most of the labor is in early October, between intensive harvests of summer and fall crops

  • They store long-term for steady sales through the winter

Sweet Potato harvest at Twin Oaks. Photo McCune Porter

They like Beauregard, and wanted to try using the single node cutting method, as advocated by Anthony and Caroline Boutard – see my Sweet Potato slideshow for details. Initially they were excited about the single node cutting process, as their roots produced exponentially more growing shoots each week. OK, maybe exponential is a bit of an exaggeration, but it gives the sense of it. Because they had so much propagation material, they started making 5-node slips, rooting clusters of cuttings in pots of compost, 3 nodes in the soil for roots, 2 nodes above ground.

Some of their single node cuttings failed to thrive, both in the trays and in the field, so they developed a 2-node cutting system instead, and also used their five-node slips. And so they had a trial of three sweet potato cutting methods, with plants in different 100 ft beds. In the past (using the regular slips method) they have averaged yields of 500-600 lbs of sweet potatoes per 100 ft bed, with a range from a poor 250 lbs to a few successes with 1000 lbs/bed. Of course, yield is not the only important feature of a market crop, although understandably it has a high profile for those growing 1500 row feet for sale.

At harvest, they found that their single-node sweet potato plants were producing a couple of hundred pounds per 100 ft bed. The 2-node beds produced about 500 pounds per bed, of relatively few, very large (6 – 20 lb) sweet potatoes. The plants with 3+ nodes in the soil gave more reasonable sized potatoes. They tend to get jumbos, so they have started planting closer (10″) to tackle this – not many customers want jumbos.

In his article in Growing for Market,  Anthony Boutard pointed out that single-node cuttings do produce fewer tubers which are larger and better formed. This is a big advantage for growers in the north, but less so in the south. The Arkansas growers have found that the 2-node cuttings are even better at this tendency in their location, which is much further south than Anthony Boutard’s farm.

Beauregard sweet potatoes saved for seed stock.
Photo Nina Gentle

Other articles in this month’s Growing for Market include Managing a cash crisis
How to climb out of the hole by Julia Shanks, the author of The Farmer’s
Office. Farmers deal with a very seasonal cash flow, and may well have gone into farming with good farming skills but not good business skills. Julia writes about four rules for getting out of a financial hole.

  1. Quit digging (don’t incur any more inessential expenses).
  2. Keep the dogs at bay (communicate with your creditors about how you plan to pay, and how you plan to keep producing the goods).
  3. Climb out (increase revenue in as many ways as possible).
  4. Get your head out of the sand (don’t panic, face realities, be proactive).

She goes on to list 10 ways to protect yourself from getting in such a hole again.

Sam Hitchcock Tilton has an article about cultivating with walk-behind tractors, ie, weeding and hoeing with special attachments. There are some amazing walk-behind
weeding machines (manufactured and homemade) throughout the world. There
is an entire style of vegetable farming and scale of tools that have been forgotten, in between tractor work and hand growing – the scale of the walk-behind tractor. The author explains how commercially available tools can be adapted to work with a BCS or a carefully used antique walk-behind tractor.

Mike Appel and Emily Oakley contributed Every farm is unique, define success your own way. Money is not the only measure. Quality of life, family time, and personal well-being are up there too, as are wider community achievements. Farming is equal parts job and lifestyle, and the authors recommend having a strategic plan for yourself and the farm, which you update every couple of years to pinpoint goals and the steps you need to take to reach them.

Cossack Pineapple Ground Cherry
Photo Southern Exposure Seed Exchange

Liz Martin writes about husk cherries (ground cherries) and how to improve production of them, to make a commercial crop viable. Who would have guessed that hillling the beds before planting can make harvest so much easier, because the fruits roll down the sides?

Judson Reid and Cordelia Machanoff wrotea short piece: Fertility tips and foliar testing to maximize high tunnel crops, and Gretel Adams wrote about  Scaling up the flower farm. Many of the ideas also apply to vegetable farms.

Mother Earth News post, Organic Broadcaster, Jamaica trip

Hoophouse early squash planted in the middle of a bed of winter chard.
Photo Bridget Aleshire

I wrote a blog post for the Mother Earth News Organic Gardening blog on Hoophouse Intercropping in Spring.

We transplant our tomatoes, peppers, squash and cucumbers into the middles of the beds of winter crops. We pull out the middle rows, dig holes, add compost and transplant. Initially the rows of winter greens to the south of the new plants shade and shelter them a little, which helps them settle in. The next week we harvest out the greens on the south side of the new crops, then after that (but less urgently) the row on the north side.

Hoophouse peppers transplanted in the north hoophouse bed among lettuce mix.
Photo Bridget Aleshire

3/15 is our usual tomato planting date, 4/1 we planted squash. 4/5 we’ll put the cucumbers in and 4/7 the peppers. We used to plant the hoophouse peppers earlier but it’s such a struggle keeping them warm enough as seedlings in the greenhouse, that we moved a week later. It’s just not worth having stunted pepper plants!

The March/April Organic Broadcaster is out too. Phew it’s hard to find enough reading time in spring! There are articles about the Organic check-off program (discussed at the MOSES Conference), information about policy work for the National Organic Program, and their “Ask a Specialist” column answering a question about “fast, inexpensive greenhouse space.” The answer was souped-up 10 x 60 ft caterpillar tunnels, including heated benches for starting plants. Other articles address organic grain production, humane mobile houses for poultry, a profile of the MOSES Farmers of the Year, Hans and Katie Bishop, solar panels on small farms, diverse meat CSA farms, as well as news from the conference. Something for everyone!

I’m volunteering with the Jamaica Sustainable Farm Enterprise Project. Here’s a bit more about the project:

The people of Jamaica and the greater Caribbean region have long been buffeted by  natural and human-caused disasters that have left them in a state of economic, social, and environmental crisis. Jamaican  people are vulnerable due to national dependency on unaffordable, less healthy, imported food, lost skill sets needed to produce certain crops without expensive chemical inputs, and natural disasters that wipe out farmers crops with regularity. The Parish of St. Thomas and the other eastern parish of Portland have systemically been the most forgotten and underdeveloped parishes in Jamaica for over a century.

St. Thomas is a farming parish. However, since the liberalization of the banana industry by the European Union and NAFTA all the banana plantations have closed leaving few agricultural avenues for profitable employment in the parish. Many of the people of St. Thomas still rely on small cash crops and seasonal tree crop production for their livelihood.

JSFEP aims to focus on local sustainable production to increase food security and help develop high value internal and export markets to increase agricultural profitability. Permaculture and organic (POF) systems provide solid foundations for these solutions.

I’ll be going to St Thomas parish (click for a map) from 5/11 to 5/22, providing training in vegetable crop planning. JSFEP partners The Source Farm, a multi-cultural, intergenerational eco-village, located in Johns Town, in the parish of St. Thomas.  You can see a slideshow at their website. And You Tube has a short video The Source Farm Foundation Ecovillage.

Well, I’m out of time this week, as I need to get my laundry off the line and spray the aphids in the greenhouse and hoophouse with soapy water.

Hoophouse slideshow, Ruminant podcast, potatoes planted

Here’s my updated Spring and Summer Hoophouse slideshow, that I promised all the people at my Organic Growers School workshops. I rearranged the slides in what I think is a better order and revised the resources section.

The Farmers Aren’t All Right.
Podcast from the Ruminant

I also took part in an interview with Jordan Marr for a podcast with The Ruminant: Audio Candy for Farmers, Gardeners and Food Lovers. It’s about farmers’ struggles with mental health problems, trying to cope with the many and varied stresses, while the public wants farmers to appear competent and blissful with all that time in the Inspiring and Nurturing Outdoors.

“Farming is tough work. The unpredictability of the job and the pressure to present a curated, bucolic version of the work can easily lead to various kinds of mental health problems: despair, feeling overwhelmed or like a failure, or even depression. In this episode, co-produced with Jessica Gale of Sweet Gale Gardens, we discuss the prevalence of mental health problems among farmers, and how to address them.” Jordan Marr

As well as Jessica Gale, the episode includes discussion of Professor Andria Jones-Bitton’s work and interviews with Jean-Martin Fortier of The Market Gardener and Curtis Stone of The Urban Farmer.

The March issue of Growing for Market is out. Nothing from me this month (I have articles for May and June/July coming up). In this issue. There are articles about No-till vegetable farming (Conor Crickmore at Neversink Farm, in the Catskill Mountains of New York), and Bio-integrated farm design by Shawn Jadrnicek, co-author with Stephanie Jadrnicek, of The Bio-Integrated Farm: A Revolutionary Permaculture-Based System Using Greenhouses, Ponds, Compost Piles, Aquaponics, Chickens and More. Lots of water in this book, and very practical. There’s an article on A DIY mobile cooler for moving and storing perishable foods  – an insulated trailer using Cool-Bot technology by Cary Rivard, Kansas State Research & Extension Horticulture & Forestry & Extension Vegetable & Fruit Crop Specialist. Karin Tifft has written The “other” reasons to grow in a greenhouse: climate, light, good use of space, reduced wastage of produce, energy conservation and more. Andrew Mefferd, the editor has written on growing cucumbers umbrella style under cover. Finally, Debra Prinzing writes on Making your mark with local branding.

Chitting seed potatoes ready for planting.
Credit Kati Folger

And here at Twin Oaks, we planted our spring potatoes yesterday, after pre-sprouting (chitting) the seed potatoes for a couple of weeks. Soon we hope to see the potato shoots emerging from the soil.

Potatoes emerging in spring.
Photo Kathryn Simmons

Hoophouse seasonal transition to tomatoes, peppers, squash, cucumbers

This past weekend I was at the Organic Growers School spring conference in Asheville, NC. I presented my workshop on Spring and Summer Hoophouses twice. This link will take you to a blog post where you can get the handout. An older version of the slideshow is at this SlideShare link. Later this week I will tweak the presentation a little and upload the revised version. It wasn’t very spring-like in Asheville. We got 3″ snow, but gardeners and farmers are a hardy lot, and attendance was still good. My workshops were packed (the room was quite small).

Young tomato plant in our hoophouse.
Photo Kathryn Simmons

Now I’m home and we had snow in the forecast for Monday night, but got ice pellets instead. The worst of the weather passed us by. It’s still very cold though, and so we are delaying transplanting our early tomatoes in our hoophouse, which we had scheduled for 3/15 and 3/16. The photo above shows where we’re headed: sturdy transplants in the middle of the bed, with wire hoops to hold rowcover on cold nights. Here’s where we are now:

March hoophouse bed prepared for tomato planting.
Photo Wren Vile

When we make the transition from hoophouse winter crops to early spring crops, we don’t clear the whole bed. First we harvest out the greens down the middle of the bed, then measure and dig holes every two feet and put a shovelful of compost in each hole. Within a couple of weeks after transplanting the tomatoes, we harvest the greens on the south side of the bed, as they will block light from the new crop. After that we harvest the greens on the north side. This allows us to keep the greens later, which covers the time (the Hungry Gap) until the new spring plantings of outdoor greens start to produce.

Tomato transplants in March, ready to plant in our hoophouse in milder weather.
Photo Wren Vile

Meanwhile the tomato transplants are in pots in our greenhouse, where we can keep them warmer at night with rowcover. Our greenhouse stays warmer at night than our double-poly hoophouse. It has a solid north wall and double-pane glass windows (old patio doors).

We use the same method for our peppers, cucumbers and yellow squash, transplanted 4/1. In the photo below you can see the winter crop of Bulls Blood beets, which we grow for leaves for salad mixes, discarded beet stems, young squash plants and one of the wire hoops that hold rowcover on freezing nights.

Young summer squash plants in the hoophouse, surrounded by Bulls Blood beets.
Photo Kathryn Simmons

In the hoophouse we have three crop seasons:

  1. winter crops planted in the fall, harvested November to April (some spinach to May)
  2. early warm weather crops planted in March and April, harvested June and July (peppers to November)
  3. high summer crops planted in July and harvested August to October.