How cold can leafy greens and salad crops survive?

Our hoophouse beds after the nights at 2F (-17C) and 8F (-13C). Looking amazing! Pam Dawling

We were luckier with the weather than many people over the weekend (12/23-12/26/2022). And so were our vegetable crops. On Friday 12/23 we prepared for a suddenly very cold night. It was very windy as we battled to stop the hoophouse windows from blowing open. We finally got some shims, a hammer and a stepladder, and wedged them closed. They stayed that way until Tuesday 12/27. We were fortunate in getting no precipitation (I hate ice!) and no power outage.

Pool noodles repurposed as draft excluders.
Pam Dawling

We fortified the doors with our rock collecting buckets, and prevented most of the under-door drafts with our pool noodle draft excluders. They have a rope running through them, which is hooked onto small cup-hooks on the door frame. We repurposed noodles that had been used as props at a party or some other kind of event. They had been covered in tube socks and had glued-on googly eyes.

Rolls of rowcover at the ready in our hoophouse.
Pam Dawling

It was a bit unnerving being in the hoophouse as it creaked and groaned in the wind. In the winter we keep rolls of rowcover ready for any night we think will be below 8F (-13C). We unrolled the rowcovers by lunchtime and laid tools on the ends nearest the doors. I was worried that if we lost power, and therefore the inflation, it would get very cold indeed in the hoophouse.

The DIY manometer in our hoophouse. (the background lines have faded). Pam Dawling

Since we last changed the plastic we haven’t managed to get the recommended 1/3” (8.5mm) pressure difference in the “bubble” between the plastic layers, compared to our normal air pressure. Mostly we don’t even get ¼” (6.5mm). The “bubble” provides thermal insulation as well as physical strength against snow or ice buildup, and strong winds.

It got down to 2F (-17C) outdoors Friday night, and Saturday didn’t warm up much. I don’t actually know what the night temperature was in the hoophouse as our recorded low temperatures don’t make sense: 14F (-10C) for four consecutive nights (Fri to Mon). I suspect we didn’t reset the thermometer correctly. Usually the hoophouse can hold 8 F (4.5 C) degrees warmer than outdoors, but not 12 F (7 C). It looks like it did, perhaps because we didn’t open it all day!

Soil thermometer in our hoophouse on 27 December 2022.
Pam Dawling

The soil is still nice and warm in there: 59F (15C). That really helps. The rowcovers are usually removed in the daytime, either pulled aside if we expect to need them again the next night, or rolled up out of the way. Most of the time they stay rolled up at the east end of the hoophouse. We appreciate not needing to deal with rowcovers most of the time! On Saturday 24th, the temperature maximum for the day outdoors was 24F (-4.5C), and we kept the rowcovers in place over the crops. On Sunday the high outdoors was 28F (-2C) so we pulled the rowcovers aside until the night. On Monday 26th the night-time forecast was benign enough that we rolled the rowcovers up. And now we get a milder spell.

Hakurei turnips with frozen yellow leaves where they touched the plastic (rowcover protected the plants). Pam Dawling

How did the crops fare? It’s not always obvious at first if a crop has been killed by cold or not, But I can now say with confidence that nothing died. The edge beds are always the coldest. The south edge bed had Hakurei turnips, delicious and notoriously the least cold-hardy turnip variety. Most of the globe of the turnip sits on the surface of the soil. You can see in the photo that some of the leaves, the ones right by the wall plastic, have been killed and turned yellow. But the roots themselves (with rowcover over them) seem fine.

Bright Lights chard with cold-damaged stems in our hoophouse north edge bed after nights at 2F and 8F
Pam Dawling

Over the other side, in the north bed, we have some Bright Lights chard, among other things. Multi-colored chards are less cold-hardy than red ones, which in turn are less cold-hardy than green ones. We know we take a risk in growing Bright Lights through the winter, but we so enjoy the sight of the short pieces of colored stems in our salad mixes that we take the risk. Some of the stems have curled over, probably on their way to dying, but the plants live on, to provide many more salads this winter! And some cooked greens too.

Some of the giant senposai leaves, where not fully protected by the relatively narrow rowcover, have developed tan dead spots, so those leaves can just continue as the plants’ solar panels until we get tired of looking at them and decide they are no longer needed.

Each winter I update my Winter-Kill Temperatures of Cold-Hardy Vegetables list, except this past spring I had nothing new to add. Outdoors, I noticed today that the tatsoi has definitely died, the Vates kale and the spinach have survived (uncovered) and the small garlic leaves don’t seem troubled. The leftover lettuce transplants have been damaged, if not killed.

Forget Miami peas; Forget industrial hemp; Optimize your Asian greens

Forget Miami peas

For years I have been mentioning “Miami Peas” in my presentations about cover crops. At the Carolina Farm Stewardship conference I was asked what they are, by Mark Schonbeck, who knows cover crops well. (This is one of the wonderful benefits of attending conferences – meeting peers and mentors, and learning new things.)
I said it is a frost tender cover crop pea of the field pea type (not a southern pea). I can’t remember where I first heard about this cover crop, and we haven’t been using it on our farm, so it was time for a reality check when I got home. I can’t find any reference to Miami peas apart from the ones I’ve made! I believe it’s a type of Canadian field pea, but maybe it no longer goes by the Miami name, or maybe it never did! It’s embarrassing to promote untruths.
Spring forage peas from Seven Springs Farm, Virginia

Pinetree Seeds says:

This short term green manure smothers weeds well and adds nitrogen and other nutrients to the soil. Peas are often mixed with vetch, oats, or rye as an effective cover crop. The sprouts are delicious and you can even harvest the peas themselves for soup. This annual prefers cool well drained soil and has no frost tolerance. Sow 3 to 4 lbs per 1000 sq. ft.

For clarity, here’s what I now believe:
  • “Forage pea” and “Field pea” are terms that include the  hardy Austrian winter peas, that we do use and are big fans of, as well as frost-tender spring peas, also known as Canadian field peas.
  • Canadian field peas are not frost tolerant and are sold by Pinetree Seeds. among others.
  • SARE lists Canadian field peas as Spring Peas. SARE is a very reliable source of information. They say

These annual “spring peas” can outgrow spring-planted winter peas. They often are seeded with triticale or another small grain. Spring peas have larger seeds, so there are fewer seeds per pound and seeding rates are higher, about 100 to 160 lb./A. However, spring pea seed is a bit less expensive than Austrian winter pea seed. TRAPPER is the most common Canadian field pea cultivar.

  • Other spring pea varieties are Dundale and Arvika
  • There’s also a tropical Pigeon Pea, Cajanus cajan, which can grow in the Southern US, but that looks pretty different, and I don’t think that’s what I meant.
Pigeon Pea flowers, Cajanus cajan
Photo Wikipedia

 

Forget industrial hemp

I have been alarmed at how many small-scale growers are trying industrial hemp. Partly I’m hoping it won’t cause a shortage in locally grown food! I also wonder how well an industrial field crop grows on a small scale, and how the growers would deal with the permits, the processing and the marketing.

Read this report from The Modern Farmer about how industrial hemp is unsuccessful for most growers and how the market is swamped with would-be suppliers:

Thousands Began Farming Hemp This Year. It Hasn’t Gone How They Hoped.

Optimize your Asian greens production

Here’s my updated slideshow on Asian greens, which I presented at the Carolina Farm Stewardship conference. 

Check their website for details about other workshop sessions too. I believe my handouts, and those of other speakers, will soon be available on their website.

Click the diagonal arrow symbol to view this full screen., and click the forward arrow to start viewing.

Senposai is our star of Asian greens. Here’s a bed of senposai outdoors in spring.
Photo Kathryn Simmons

Garden Planning, Winter Harvests and Speaking Events

Garden Planning Field Manual
Photo VABF

‘Tis the season – after the relaxation of the holidays – time for garden planning. Inventory your seeds left from last year, peruse the catalogs and prepare your seed orders. The earlier you get them in, the more likely you are to get the varieties you want, before anything is sold out.

I notice that readers of my blog have been looking up the Twin Oaks Garden Calendar,  also known as The Complete Twin Oaks Garden Task List Month-by-Month. You can search the category Garden Task List for the Month, or you can click on the linked name of the month you want. At the end you can click on “Bookmark the Permalink” if you might want to refer to this in future. Remember, we’re in central Virginia, winter-hardiness zone 7a. Adjust for your own climate.

Meanwhile, despite the turn to cold weather, we are not huddled indoors all the time. Each day, one or two of us sally forth to harvest enough vegetables to feed the hundred people here at Twin Oaks Community. Outdoors, in the raised bed area, we have winter leeks, Vates kale, spinach and senposai. We could have had collards but we lost the seeds during the sowing period, so we have lots of senposai instead. Senposai leaves (the core of the plant may survive 10F), are hardy down to about 12F. I noticed some got a bit droopy when we had a night at 15F. Collards  are hardier – Morris Heading (the variety we grow) can survive at least one night at 10F.

Hoophouse December View
Photo Kathleen Slattery

In the hoophouse, we have many crops to choose from: lettuce, radishes, spinach, tatsoi, Yukina Savoy, Tokyo Bekana, turnips and turnip greens, scallions, mizuna, chard, Bull’s Blood beet greens.

Hoophouse scallions ready to harvest.
Photo Pam Dawling

Pak Choy and Chinese cabbage heads are filling out, ready for harvest in January.

Tokyo Bekana, a non-heading Asian green,  has large tender leaves, which we are adding to salad mixes. It can be used as a cooking green, but only needs very light cooking. It will bolt soon, so we are harvesting that vigorously, not trying to save it for later.

The kale and senposai in the hoophouse are being saved for when their outdoor counterparts are inaccessible due to bad weather. The spinach is added to salad mixes, or harvested for cooking when outdoors is too unpleasant, or growth slows down too much.

Hoophouse winter lettuce: Green Forest and Red Salad Bowl, two of our fifteen varieties.
Photo Wren Vile

Another kind of planning I’m doing right now is scheduling my speaking events for the coming year and practicing my presentations. Last week I updated my Events page, and this week I’m adding a new event: The September 21-22 Heritage Harvest Festival.

I might pick up a couple of events in late April and early June, but that’s just speculation at this point.

Right now I need to practice for the CASA Future Harvest Conference January 11-13. Cold-hardy Winter Vegetables and a 10-minute “Lightning Session” on using graphs to plan succession plantings for continuous harvest. Click the link or my Events page for more on this.

Komatsuna: Asian greens for September, plus Chinese Kitchen Garden book

Komatsuna Asian green.
Photo Fothergill Seeds

Komatsuna is a large, upright, hardy, leafy green, also known as mustard spinach (so is Pak Choy!), and Summer Fest (a popular hybrid). It’s available in green,  or red (purple) from Kitazawa. it grows into a large plant 18″ (45 cm) tall, with tender deep green leaves, sturdy petioles and a flavor that is mildly peppery, not pungent. You can pick and bunch individual leaves, or harvest the whole plant. You can instead harvest at baby salad size 21 days from sowing. It reaches full size in only 35 days. The days to maturity lengthen as the weather cools.

The hybrid variety Green Boy is preferred by Japanese growers because of its cold tolerance, meaning it can be grown year round in mild areas.  Green Boy is good for hoophouse production in winter. The hybrid variety Summer Fest is best for growing in late spring into summer, rather than in fall and winter. Open-pollinated komatsuna is available from Evergreen Seeds. These two Asian seed companies sell the dark green glossy type. Some other companies have paler green unglossy vegetables called komatsuna that look different to me: Baker Creek, (who call it Tendergreen, which is sometimes considered a separate vegetable), StokesHudson Valley.

Komatsuna is cold-tolerant to 15°F (-9.5°C), perhaps 10°F (-12°C). For seed-savers and botanical Latin geeks, it’s Brassica rapa var. perviridis (Kitazawa) or Brassica rapa var. komatsuna (sources vary in their classification.) Komatsuna is one of the parents of my all-time favorite Asian green, senposai.

Komatsuna transplants.
Photo Gardening Know-How

Amy Grant writes about komatsuna on the Gardening Know-How site

Like all Asian greens, komatsuna has similar care requirements to other brassicas. Very fertile soils grow the best Asian greens, and they are shallow rooted, so pay extra attention to providing enough water during hot weather to prevent bitter flavors and excess pungency. Sowing in the fall will mean most of us won’t have to worry about too much hot weather. For central Virginia we would sow 8/20-9/15 for outdoors, 9/15-10/15 outdoors to transplant into a hoophouse. It could be sown later in the hoophouse for filling gaps as they appear during the winter. Or sow indoors in early spring to grow in a hoophouse or greenhouse. Komatsuna is relatively bolt resistant, but don’t wait for hot conditions to harvest, or you could end up with a bunch of yellow flowers instead of tasty leaves.

Cover the sowing with insect net or rowcover if you have a lot of late summer brassica pests (harlequin bugs, I’m talking about you!). If direct sowing, you can thin to 4″ (10 cm) apart for adolescent leaves to use like spinach. Thin to 8″ (20 cm) for mature plants, which can be cut as “heads” to be  stir-fried or steamed. Komatsuna does not form true heads, so don’t wait for that!

If you are sowing to transplant, do that when the plants are 3-4 weeks old (in spring they would need 5-6 weeks). Give the plants 8″ (20 cm) of space all round, or as much as 12″ (30 cm) if you plan to harvest after the plants reach full size. Water well, depending on rainfall. Aim for an inch a week.


At the Heritage Harvest Festival this past weekend, I went to a great workshop by Wendy Kiang-Spray, with show-and-tell vegetables. She has a book, The Chinese Kitchen Garden, published by Timber Press, who say:

“she beautifully blends the story of her family’s cultural heritage with growing information for 38 Chinese vegetables—like lotus root, garlic, chives, and eggplant—and 25 traditional recipes, like congee, dumplings, and bok choy stir-fry. Organized by season, you’ll learn what to grow in spring and what to cook in winter.”

I haven’t read it yet, and I’ve no idea if she mentions komatsuna, but for lovers of Asian vegetables this book is a valuable new addition, and I appreciate that it is seasonal and combines growing with cooking.

Asian Greens for August: fall senposai, winter Yukina Savoy

 

Brassica seedlings under insect netting.
Photo by Bridget Aleshire

In late June and early July, we sow nursery beds of brassicas for transplanting outdoors. In the photo above, the plants at this end of the bed are cabbages, but in the same bed there are also Asian greens for fall and early winter harvests. We cover the beds with ProtekNet, which I already told you about in my Asian Greens for July post.

We sow the seeds about 3/inch, sowing about a foot of nursery bed row for each 12-15 feet of final crop row we want. And we sow twice, a week apart, to cover contingencies like poor germination or needing to replace casualties a week later. We transplant them three weeks after sowing, at the end of July or in early August.

Brassica beds covered with ProtekNet insect netting.
Photo Wren Vile

We cover the beds of transplants with more ProtekNet, for the first month. This is part of our strategy for dealing with harlequin bugs. We try to have August be “No Visible Brassicas Month” – we remove the old spring brassicas, or till them under, and we keep all new brassicas under cover. We hope that a month or more with no food (except cleomes) will stymie the harlequin bugs lifecycle.

We grow Yukina Savoy for harvests from mid-October to mid-November (more on that in November), and senposai for harvests from August 20 to November. Any day now we can start harvesting senposai! Both these crops get followed by a supply from the hoophouse (more on that in late winter).

Senposai transplants
Photo Wren Vile

I know it’s only three months since I last wrote about senposai, and here it is again! If you ran out of seeds in the spring, or this is a new vegetable for you, hurry and order from Fedco Seeds in Maine. Their order deadline is October 31 for this year. Also available from Kitazawa Seeds or Evergreen Seeds

For fall harvests, sensposai is ready a mere 40 days from sowing, or 10 days longer if you disturbed it and transplanted, as we do. Depending on your winter climate zone, you may have time to sow for growing in a hoophouse (zone 6 or warmer), or outdoors (zone 8?). If you had a cabbage disaster, try fast-growing senposai.

An outdoor bed of young Senposai.
Photo by Wren Vile

Senposai is an F1 hybrid, so don’t try saving your own seed, if you want reliable production. It was developed in Japan, and is a cross between Japanese Mustard Spinach (Komatsuna Brassica rapa – more on this next month) and regular cabbage. Senposai has big round medium-green leaves, and an open growth habit. It needs a generous 12″–18″ spacing, unless for some reason you want to limit the generous size of the leaves. The flavor is sweet and the texture is tender. Photo by Fedco Seeds. As a Fedco customer reports:

“Customers buy it once because it looks absolutely stunning, then they buy it again because it is extremely delicious. Absurdly productive and easy to grow”

Senposai leaves are cold-tolerant down to 12F (-11C), and the core of the plant may survive 10F (-12C). Young plants can be used for salads.

Asian Greens for July: Maruba Santoh, plus sowings for fall

Young Maruba Santoh plants
Photo by Ethan Hirsh

In June I told you about Tokyo Bekana, a light green tender-leaved, white-stemmed green which can be cooked, or used as a substitute for lettuce in hot weather. Because summer in Virginia is a hard time for leafy greens, July’s Asian green is very similar – Maruba Santoh. Maruba Santoh has smoother, wavy, less ruffled leaves than Tokyo Bekana.

To show you I’m not being a slouch, I’ll include some pointers on sowing Asian greens for fall, because now is the time – in our climate at least. Here’s what one of my favorite seed suppliers, Fedco Seeds has to say:

Maruba Santoh (35 days) Brassica rapa (pekinensis group) Open pollinated. With Maruba you get four vegetables in one. The loose round vibrant chartreuse leaves provide a mild piquant mustardy flavor while the flat white stems impart a juicy crisp pac choy taste. High-end chefs like to use the blossoms. Market grower Scott Howell finds the flavor more subtle and complex than that of other greens and cuts Maruba small for his mesclun. Fairly bolt tolerant, so plant after the early spring flea beetle invasion subsides.

Harlequin bugs.
Photo University of Maryland Extension Service

Fedco is in Maine and we’re in Virginia, so things are a little different. The information on their website about pests and diseases is good. Our worst brassica pests are harlequin bugs.

We grow our summer brassica seedlings and transplanted Asian greens under ProtekNet on hoops. On the Dubois link, study the Dimensions and Specifications tab, then download the brochure from that tab. Study the Descriptions tab – it tells you which insects are excluded by each size mesh. Be sure that you choose the right size mesh for the bugs you want to exclude. Flea beetles and thrips are small – you need a small mesh. Johnny’s is now marketing the close-mesh ProtekNet as  “Biothrips” insect netting, and they also have a comparison chart of rowcover and insect netting on their site.

Adolescent Maruba Santoh plants bunched for market.
Photo Kitazawa Seeds

Kitazawa Seeds also sells Maruba Santoh seed, under the Chinese Cabbage heading. Like most brassicas, Maruba Santoh does best in cool weather, although it is somewhat heat tolerant (or “warm tolerant” as we call it in Virginia.) It tolerates heat better than Napa Chinese cabbage does. To avoid bolting, keep the plants above 50F (10C) at all times, but particularly avoid prolonged spells below this “bolting trigger” temperature.

Maruba Santoh will germinate at temperatures between 50-85F. Seedlings emerge in just 3 days in summer. For summer use, direct sow, thin the rows for baby salad mix, then let the “heads” (it doesn’t actually head up) develop to full size (6-10″ tall) after about 35-40 days. Or transplant two week old starts. We tend to grow our plants quite big (12″ tall) and harvest by the leaf, several times over. Maruba Santoh makes a fine substitute for lettuce, and a tasty quick-cooking green.

To calculate sowing dates, work back 40 days from when you want to harvest, and sow more every week or two until you run into the fall slowdown temperatures, or you go back to eating lettuce in salads and cooking chard and kale. If you still have Maruba Santoh growing in the fall, know that it will be frost tolerant to 25°F (-4°C). No hurry.

Newly transplanted Maruba Santoh.
Photo Ethan Hirsh

Maruba Santoh can also be grown at other times of year: spring and fall outdoors, winter in the hoophouse. The seedlings have large cotyledons and make good microgreens too.

Kitazawa’s  Culinary Tips include: Use in salad, sukiyaki, ohitashi, yosenabe, stir-fry, soup and pickling. Kim chi here we come! (If we had surplus.)


Next month I will talk more about Asian greens outdoors in fall. Now is the time to sow for fall harvests. We start in late June, and sow more in early July. We always make two sowings a week apart, for insurance.  We are aiming for greens to feed us in early fall, before the kale is ready, and into the winter, harvesting by the leaf. But Asian greens can be sown all the way up to two months before your first fall frost date. For us, that means August 14-20.  If you want to make sowings now, consider senposai, komatsuna, pak choy, tat soi, Yukina Savoy, and Chinese cabbage.


An insectary circle with borage and sunflower in a chard bed.
Photo Bridget Aleshire

I have two posts on the Mother Earth News Organic Gardening Blog that I haven’t told you about yet. So if it’s too hot out, or it’s raining (don’t make me envious) seek shade and read more. The newer post is Insectaries: Grow Flowers to Attract Beneficial Insects, and the previous one is Planting Leeks. 

Hoophouse winter greens, transplanting spinach, crocus flowering

Russian kale, yukina Savoy and lettuce from our winter hoophouse .
Photo Wren Vile

Our hoophouse is bursting with winter greens. We just decided to hold back on harvesting our outdoor Vates kale and focus on the greens  which are starting to bolt in the hoophouse. That includes the last turnips (Hakurei, Red Round and White Egg), Senposai, tatsoi, Yukina Savoy, mizuna, Ruby Streaks, Scarlet Frill and Golden Frills mustards. Big but happily not yet bolting are the spinach, Rainbow chard and Russian kales. A row of snap peas has emerged. Time to stake and string-weave them!

The lettuce situation is changing as we are eating up more of the overwintered leaf lettuce in the hoophouse. The lettuces in the greenhouse have all gone, to make way for the flats of seedlings. Plus, we needed the compost they were growing in, to fill the flats. More about lettuce in February next week.

We have also cleared the overwintered spinach in one of our coldframes, so we can deal with the voles and get them to relocate before we put flats of vulnerable seedlings out there. The voles eat the spinach plants from below, starting with the roots. We had one terrible spring when they moved on to eat the baby seedlings when we put those out there. After trial and error a couple of years ago, we now clear all the spinach from one frame, then line the cold frame with landscape fabric (going up the walls a way too), wait two weeks, then put the seedlings out on top of the landscape fabric. The voles by then have decided nothing tasty is going to appear there, so they move on.

Spinach over-wintered in our cold frame
Photo Wren Vile

Outdoors, we have just started transplanting new spinach. We have four beds to plant, a total of  3600 plants, so we have to keep moving on that! We are trialing several varieties again, as we did in the fall. We have the last Tyee, alongside Reflect and Avon this spring. Inevitably things are not going perfectly according to plan. Yesterday I forgot to follow the plan, and we started with Avon and Tyee at opposite ends of a bed we had planned to grow Reflect in! Anyway, we are labeling everything and hoping to learn which have best bolt resistance. Watch this space.

We have grown our spinach transplants (as well as kale and collards) in the soil in our hoophouse, sowing them in late January. I wrote about bare root transplants in early January this year. You can find more links and info in that post. Growing bare root transplants saves a lot of work and a lot of greenhouse space.

For those relatively new to this blog but living in a similar climate zone, I want to point you to The Complete Twin Oaks Garden Task List Month-by-Month. It includes a link for each month’s task list. I notice from the site stats that some of you are finding your way there, but now there are so many years’ worth of posts it’s perhaps harder to find. Happy browsing!

Following on from last week’s mention of harbinger weeds of spring: chickweed, hen-bit and dead-nettle, I can now report that I’ve seen a flowering crocus (2/17), another marker on our phenology list. The average date for first crocuses here is February 8, so they are later than usual. I did notice however, that the foot traffic over the patch of grass has been heavier than usual.

Anne Morrow Donley sent me a link to WunderBlog®, the blog from Wunderground, my favorite weather forecast station, to an article by Bob Henson: This is February? 80°F in Denver, 99° in Oklahoma, 66° in Iceland, 116° in Australia. It includes a map of the Daily Spring Index Leaf Anomaly, Figure 1.

Image credit: USA National Phenology Network via @TheresaCrimmins.

Figure 1. An index of the seasonal progress of leafy plants shows conditions 20 days or more ahead of schedule over large parts of the South and Southwest as of Sunday, February 12. Image credit: USA National Phenology Network via @TheresaCrimmins.

The post has lots of other interesting weather info too. Thanks Anne!


I remembered another of the items lost in the hacked post a few weeks ago: My Mother Earth News Organic Gardening Blogpost on Heat Tolerant Eggplant Varieties made it into their 30 Most Viewed blogposts for 2016. I’ll be writing up more about those varieties, linking the 2016 results to the weather each week (especially the temperatures) and adding what I learn in 2017.

Bare Root Transplants

Lettuce seed bed, with Muir, Jericho, Sierra lettuces. Photo Bridget Aleshire
Lettuce seed bed, with Muir, Jericho, Sierra lettuces.
Photo Bridget Aleshire

Last week when writing about Lettuce Varieties for January I mentioned how we grow all our outdoor lettuce as bare root transplants. From January through to the end of April, we sow lettuce seed in open flats. After that date, we sow in outdoor nursery seed beds, and simply dig up the transplants when big enough and replant them in our raised beds. We transplant 120 lettuce outdoors each week until early October and then transplant in our greenhouse and our hoophouse. We also grow many other crops (all the easy to transplant ones) in open flats, or in nursery seed beds.

This method has gone “out of fashion”, but perhaps it will come back in! Atina Diffley (Author of Turn Here Sweet Corn and Wholesale Success) has written a blog post about bare-root brassica transplants at atinadiffley.com/blog/. She has written a thorough-and-concise 9 page manual Seed Beds: Bare Root Field-grown Brassica Transplant Production.  It includes a chart of pros and cons of bare-root transplants compared to container-grown greenhouse transplants.

Using bare-root transplants does require a bit more attention to technique than popping plugs into the ground. But it’s not that difficult and we train new people every year with success.

Why bare-root transplants?

Bare-root transplants save a lot of time and money, compared to growing in flats. They also save on valuable greenhouse space. The plants get very sturdy, because they have the full depth of soil in which to develop big roots. Starts grown in outdoor seedbeds are already acclimated to cooler conditions than plants in your greenhouse. They are less prone to drying out than seedlings in flats, but do be ready to protect them from bugs.

Which crops work best?

Bare-root transplants can suffer more transplant shock than plugs, so start with “easy to transplant” crops, such as brassicas (cabbage, kale, collards, broccoli, Brussels sprouts, kohlrabi), lettuce, onions and leeks. Tomatoes and peppers are worth trying next. See the Chart “Relative Ease of Transplanting Bare-Root Vegetable Seedlings” free online in Knott’s Handbook for Vegetable Growers. Avoid trying bare-root cucurbits (squash, melons, cucumbers).

Bare-root transplants can be used on any scale, from backyard to large farm. See the impressive photos of huge beds of cabbage transplants in Atina Diffley’s manual. They can be used at various times of year, and from indoors to outdoors and vice-versa.

Spring bare-root transplants started in a hoophouse, planted outdoors.

For the earliest spring transplants, bare-root hoophouse starts are a nice option. For us, onion seedlings overwintered in the hoophouse have worked very well. Seedlings outdoors or in a cold-frame suffer too much winter-kill. We don’t want to fuss with flats in November-February. We’re in zone 7, at 38̊ N. We sow onions in the soil in the hoophouse November 10 and 20, with a backup sowing on December 5. We plant them outdoors as early in March as we can. The onions get to thin-pencil-size by March 1, which we couldn’t do from a spring sowing. Onion roots are tough and thick, not thread-like – they are easy as bare-root transplants.

We sow spinach, collards and kale in the hoophouse in mid-late January and plant them outdoors in early March. This is a lot less work than using flats, and our comparison trials with bare-root spinach showed results were just as good as spinach in Speedling plug flats. We have tried early lettuce transplanted from the hoophouse, but the plants were not as sturdy as those in flats.

Senposai, the Thousand Wonder Green, Credit Kathryn Simmons
Senposai, the Thousand Wonder Green,
Credit Kathryn Simmons

Outdoor bare-root transplants

See my book Sustainable Market Farming, for more details of growing outdoor bare root transplants. We grow lettuce this way from April to September, and fall brassicas in June and July, in one of our permanent raised beds where the soil is friable and free-draining. Also see Atina Diffley’s manual for cultivation tips.

We grow outdoor cabbage, broccoli, collard, senposai and Yukina Savoy transplants in seedbeds for 3-4 weeks in June and July, covered with ProtekNet on hoops. We transplant in July and early August for harvest in October and November. We prefer this to direct sowing, because it is much easier to keep the relatively small seedbed watered and bug-free. For large amounts use an EarthWay seeder. Atina Diffley recommends the leek seed plate for brassicas.

Outdoors to indoors

In September we make an outdoor seedbed for crops to transplant into our hoophouse in October. The late summer hoophouse crops get a few extra weeks to finish up. Because the hoophouse can be warmer than ideal for lettuce germination until well into fall, it often works better to start plants in a cooler location, then move the plants. In September in our climate, four-week old lettuce plants will be a good size.

As well as ten varieties of lettuce, we sow various Asian greens and Brite Lites chard. Nine days later we sow another ten varieties of lettuce, white and red Russian kales, senposai and frilly mustards such as Ruby Streaks, Red Rain, Golden Frills, Scarlet Frills as well as green mizuna. We cover the seedbeds with hoops and ProtekNet and water daily. Transplanting these plants starts October 1 with the fast-growing pak choy, Chinese cabbage and Tokyo Bekana. The other transplants follow, as they reach the right size.

Brassica seedbed protected from insects with ProtekNet and hoops. Photo Bridget Alsehsire
Brassica seedbed protected from insects with ProtekNet and hoops.
Photo Bridget Alsehsire

Stay indoors in winter

In October in the hoophouse we sow short rows of “brassica fillers”, mostly senposai, Tokyo Bekana and Maruba Santoh. These grow fastest, which becomes more important in the dark winter days. We fill gaps in any brassica bed, that occur either because of disease, or of harvesting. In late October and early November we sow filler leaf lettuce varieties and filler spinach. These extra plants help us out if something goes wrong, and give us the chance to grow some extra crops after the first ones have been harvested.

How much to sow

Our formula for sowing seedbeds in the hoophouse is to divide the final row length of brassica plants by 10 to give the minimum length of seed row to sow. These plants will be transplanted 10″-12″ (25-30 cm) apart. For onions (to be transplanted 4″ (10 cm) apart), we divide the number of plants wanted by 20 to give the row feet (67/m), but we sow this amount twice, about 10 days apart. Outdoors for the fall brassicas, we sow around a foot (30 cm) of seed row for every 12′-15′ (3.6-4.6 m) of crop row, aiming for 3-4 seeds per inch (0.75 cm apart). These plants will be transplanted 18″ (46 cm) apart. It’s important to weed and thin the seedlings to 1″ (2.5 cm) apart soon after they emerge.

Transplant age and size

There is quite a lot of flexibility about when a start can be transplanted, but there are accepted ideals to be aimed for. The University of Florida Vegetable Horticulture Program Vegetable Transplant Production page  has a wealth of transplant information. Transplants grown over winter or in very early spring in a hoophouse will take longer to reach plantable size than those sown in spring or summer.

Suitable conditions for transplanting

The ideal conditions for outdoor transplanting are mild windless afternoons and evenings just before light steady rain. Transplanting late in the day gives the plant the chance to recover during the cooler night hours when transpiration is slower. Shadecloth or rowcover can reduce the drying effects of wind and sun. Damp soil is important before, during and after transplanting.

Bare-root transplanting technique

When you dig up your bare-root transplants, leave some soil clinging to the roots, to help the plants re-establish quicker. They don’t need a full handful of soil for each plant. Just dig up a clump and give it a light shake, to leave the majority of the soil behind, and some still on the roots. This means less damage to the root hairs. Be sure to dig deep enough so you don’t damage the tap roots. Water your plants the day before and an hour before lifting (pulling) them. In hot weather, keep the plants as shaded as possible while transplanting.If necessary water the soil ahead of planting.

We use plastic dish-pans to carry our plants from seedbed to field, and I tell people to only dig up what they think they can transplant in half an hour, so that plants don’t sit around for too long. Push the trowel into the soil, using the dominant hand, push it forwards, shake a plant loose from the clumps in the dish-pan with the other hand, and slip a plant in behind the trowel. Pull out the trowel, keeping it in your hand while you close the soil against the stem with your planting hand and the trowel. (Efficient workers keep a hand on the trowel at all times, never setting it down.) Move to the next spot and repeat. When setting out a large number of plants, water every 20-30 minutes if you don’t have drip irrigation running (a bit less often if you do) regardless of the number of plants set out. If the person is skilled and moving fast, and the weather is not outrageously hot or windy, I might let an hour go by before pausing to water. The advantage of getting a lot of plants in the ground proficiently and quickly might outweigh the need to water more often, as the plants are not having their roots exposed to the air for as long when they are planted fast. The hand-watering really helps the soil settle around the roots, and after that the damp soil can wick moisture from the irrigation towards the plant.

Aftercare: water, rowcover, shadecloth

Water your plants the day after transplanting, on days 3, 7 and 10, and then weekly, if it doesn’t rain when you’d like it to. Shadecloth draped over recently transplanted crops can help them recover sooner from the shock in hot sunny weather. We use 50% shade, in 6′ (1.8 m) width, with wire hoops to hold the shadecloth above the plants. This improves the airflow as well as reducing the abrasion or pressure damage done to the plants. The airflow through shadecloth is better than with floating rowcovers. ProtekNet allows good airflow too, and keeps bugs off.

Shade cloth on lettuce seed bed. Photo Nina Gentle
Shade cloth on lettuce seed bed.
Photo Nina Gentle

 

 

 

Mid-winter hoophouse harvests

December 29 hoophouse crops Photo Kathleen Slattery
December 29 hoophouse crops
Photo Kathleen Slattery

Here we are in the shortest days. What are we harvesting from our hoophouse (high tunnel)?  Many different crops, mostly leafy greens, but with the addition of radishes, turnips and scallions. I’ll start with those.

White Icicle radish Photo Southern Exposure Seed Exchange
White Icicle radish
Photo Southern Exposure Seed Exchange

We’re harvesting our third sowing of radishes, sown on 10/30. We like the vari-colored Easter Egg radishes and the long White Icicle for this time of year. Cherry Belle also works in this sowing, but not later. Like Sparkler, it gets too fibrous in winter.

Our favorite scallions are Evergreen Hardy White, which are extremely cold tolerant. They are also slow to grow. We are starting to harvest the ones we sowed 9/6. The second sowing (which followed the first radishes on 11/18) are just spindly little blades so far.

Hakurei turnips Photo Small Farm Central
Hakurei turnips
Photo Small Farm Central

The turnips (and their greens) which we are starting to harvest at tangerine-size, are Hakurei and Red Round, from a 10/14 sowing. We made a second sowing of turnips on 10/26, but we over-watered them and got patchy germination. We filled the gap with a late sowing of brassica salad mix. This is a mixture of random leftover brassica seeds (varieties we didn’t like, seed that is getting a bit old) which we sow and then cut with scissors about an inch above the soil once they get to about 4″ tall.

Baby lettuce mix in the hoophouse. Photo Twin Oaks COmmunity
Baby lettuce mix in the hoophouse.
Photo Twin Oaks Community

Just like baby lettuce mix. We are on our second cut of our 10/24 lettuce mix. We buy the mix already made, although if we get close to running out of seed, we have been known to mix in some seed of basic varieties like the Salad Bowls, that do well in the winter high tunnel. We also have lots of big lettuce plants. We take leaves off those for our salad mixes when we don’t have baby lettuce mix at the right stage for cutting.

Ruby Streaks beside green mizuna. Credit Ethan Hirsh
Ruby Streaks beside green mizuna.
Credit Ethan Hirsh

Into the salad mix we add chopped mizuna and its spicier cousins Golden Frills, Ruby Streaks and Scarlet Frills. These add loft, visual interest and flavor. For color we also add chopped Bulls Blood beet leaves and chopped small leaves of Brite Lites chard. As well as mixing the colors and shapes, I try to have at least one representative of each of three crop families: spinach, chard and beets; lettuce; brassicas such as mizuna, baby kale leaves, small leaves of Tokyo bekana, Yukina savoy, tatsoi.

Tatsoi in the hoophouse Photo Wren Vile
Tatsoi in the hoophouse
Photo Wren Vile

For cooking greens we are harvesting leaves of Russian kale (transplanted 10/22), our first chard  (transplanted 10/16), spinach (sown 9/6 and 10/24), senposai (transplanted 10/24), Tokyo bekana (transplanted 10/9) and Yukina savoy (transplanted 10/24). it takes 10 gallons of greens to provide 100 people with a healthy serving each. We aim to provide the cooks each day with a choice of two or three different cooking greens.

We are also harvesting some greens as whole heads now. We are clearing our first planting of tatsoi (sown 9/7), which has been getting ready to bolt for a couple of weeks now.  Likewise the Tokyo bekana, which starts to bolt at the end of December.

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

 

We are also cutting big heads of Chinese cabbage and Pak Choy.  As we harvest these, we fill the gaps at the end of the day with replacement plants. My current favorite is senposai, as it is very quick to grow and can be eaten at any stage. (And of course, it’s very tasty, otherwise I wouldn’t even mention it!) We reckon 12/31 is the last worthwhile date for us to do this gap filling with Asian greens. After that we use spinach or lettuce transplants up till 1/25, then only spinach (up till the end of February). We’ve found that planting after those dates doesn’t produce harvest, just wasted time!

The Yukina savoy doesn’t really start bolting until the last week of January normally, but with the freakish warm weather we’ve had this December, we might get early bolting. I don’t know if this crop bolts mostly in response to day length or to temperature. I guess we’ll find out.

We’ve ordered our seeds, we’re planning our next hoophouse crops and our schedule for sowing seedlings in the greenhouse. And this is the slow season!

Bulls Blood beets add intense color to salad mixes. Photo Wren Vile
Bulls Blood beets add intense color to salad mixes.
Photo Bridget Aleshire

 

Insurance crops that are there when you need them

Swiss Chard Photo Small Farm Central
Swiss Chard
Photo by Small Farm Central

You might think I wrote a typo for crop insurance, but no. There are some reliable vegetable crops that grow without much attention and quietly wait until needed. Chard is one of those. We sow chard in April, after the early spring rush. We plan for it to provide us with leafy greens in the summer, after the brassicas have bolted. We prepare a bed, unroll hay mulch over it, then make “nests” in the hay for planting. Nests are holes in the hay down to soil level, at each spot where we want to plant. After transplanting. we water and tuck the hay tight around the plants to keep the weeds at bay.

Some years there isn’t much demand for chard and we just leave it growing. If we need it, there it is with a generous supply of leaves. If we ignore it, nothing goes wrong. It’s worth having some crops like this in the garden, to help ensure there’s always something to eat.

Malabr spinach Photo by Southern Exposure Seed Exchange
Malabar spinach
Photo by Southern Exposure Seed Exchange

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

Purple-podded asparagus bean Photo by Southern Exposure Seed Exchange
Purple-podded asparagus bean
Photo by Southern Exposure Seed Exchange

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

West Indian gherkins on a trellis. Photo by Nina Gentle
West Indian gherkins on a trellis.
Photo by Nina Gentle

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

Tokyo bekana Photo by Johnnys Seeds
Tokyo bekana
Photo by Johnnys Seeds

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

And for leafy cooking greens, senposai does well in spring and fall outdoors, and in our hoophouse in the

Senposai. Photo by Kathryn Simmons
Senposai.
Photo by Kathryn Simmons

winter. It’s fast-growing, productive, disease-resistant, easy to cook and delicious to eat.  In spring it needs an early start in our climate, so that it has time to be productive before it bolts. In fall it’s cold-hardy down to 12F. This fall, though, we found its Achilles Heel – the senposai became an unplanned trap crop for Harlequin bugs! We did spend time every day for a while squashing the bugs on the senposai leaves, and we made a difference in the number of bugs. But we lost the senposai.

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