I have had a little flurry of arranging workshops, so if you have (educational) travel plans, check out my Events page. I’ve also got two interviews lined up, for podcasts, and I’ll tell you about those when they go online.
Use cover crops to feed and improve the soil, smother weeds, and prevent soil erosion. Select cover crops to make use of opportunities year round: early spring, summer, fall and going into winter. Fit cover crops into the schedule of vegetable production while maintaining a healthy crop rotation.
In the Main Conference, on Sat Nov 2, 1.30 – 2.45 pm in the Empire Ballroom E, I have a 75 min workshop
Optimize your Asian Greens Production
This workshop covers the production of Asian greens outdoors and in hoop houses in detail, for both market and home growers. Grow many varieties of tasty, nutritious greens easily and quickly, and bring fast returns. The workshop includes tips on variety selection of over twenty types of Asian greens; timing of plantings including succession planting when appropriate; crop rotation in the hoop house; pest and disease management; fertility; weed management and harvesting.
I will be participating in the Booksigning on Saturday 5.45 – 6.45 pm during the reception
Winter Cover Crops
Cover crops have been much on my mind. Partly it’s that time of year – too late for us to sow oats, not so late that the only option left is winter rye. Here’s my handy-dandy visual aid for central Virginia and other areas of cold-hardiness zone 7a with similar climates.
If you are considering growing winter rye as a no-till cover crop this winter, check out this video:
Rye Termination Timing: When to Successfully Crimp, by Mark Dempsey
“Interested in no-till production, but unsure of how to manage cover crops so they don’t become a problem for the crop that follows?
The most common management concern is when to crimp your cover crop to get a good kill but prevent it from setting seed. Getting the timing right on crimping small grain cover crops like rye isn’t difficult, but it does take a little attention to its growth stage. See this three-minute video for a quick run-down on which stages to look for in order to get that timing right.”
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.
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 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.
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!
Our goal is to keep the space filled with useful crops.
Success with this goal relies on a cluster of strategies
The fall transplant program I describe above.
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
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.
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
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 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.
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.
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)
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.
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
Gather sowing and harvest start and finish dates for each planting of each crop you are growing as successions.
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.
From your first possible sowing date find the first harvest start date.
Decide the last worthwhile harvest start date, mark that.
Divide the harvest period into a whole number of equal segments, according to how often you want a new patch.
Mark in the harvest start dates and see the sowing dates that match those harvest dates
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!).
After the set-backs with our winter hoophouse greens transplants that I wrote about last week, we worked really hard and got the whole house planted up. Most of the transplants have recovered from their transplant shock (wilting each day), during the cloudy weather we had.
The new seedlings are coming up fast and calling on us to thin them. We ended up not needing so many of thePlan D plug flat plants, but we’ve kept them for now “in case” .
Ultimately if we don’t need them, they’ll go in a salad mix. I wrote about making salad mix last year. The past two days I have been able to harvest a mix in the hoophouse. The ingredient we are shortest of is lettuce. My first mix was spinach, Bulls Blood beet leaves, a few leaves of Tokyo Bekana, Bright Lights chard, Scarlet Frills, Ruby Streaks and Golden Frills, and a handful of lettuce leaves. Red Tinged Winter is growing fastest, of all the varieties we planted this year.
The mix I made today had fewer ingredients. I left the frilly mustards, the lettuces and the Tokyo bekana alone to grow some more. I used Bulls Blood beets, spinach, tatsoi outer leaves and a few Bright Lights chard leaves and stems.
In April, sadly, our last mizuna and ferny mustards will come to an end. In our hoophouse we do three plantings of these frilly leaved greens, which we use for salads all winter and early spring.
Mizuna (also known as kyona and shui cai) is a Brassica rapa var. japonica, meaning it’s in the turnip family. The other frilly mustards, such as Ruby Streaks, Golden Frills, Red Rain are Chinese Mustards, B. juncea. We tend to treat them as if they are all types of mizuna. True mizuna is available in green or purple (but Ruby Streaks and Scarlet Frills mustards are much better colors than Purple Mizuna.)
All are very easy to grow, can be transplanted or direct-sown, and tolerate cold wet soil. They are ready to be harvested for baby salads only 21 days after sowing in the fall (longer in winter). They grow to maturity in 40 days. They are easy-going vegetables, fairly heat tolerant (well, warm tolerant) and cold-tolerant to 25°F (-4°C). All regrow vigorously after cutting. The ferny leaves add color and loft in salad mixes, as well as an attractive leaf shape.
Mizuna is very mild-flavored. The ferny mustards vary in pungency, but most only become markedly spicy when they start bolting.
Like all Asian greens, they need similar care to other brassicas, doing best in very fertile soils. They are shallow-rooted – pay extra attention to providing enough water during hot weather to prevent bitter flavors and excess pungency, especially with the B. juncea ones. Provide 1” (2.5 cm) of water per week, 2” (5 cm) during very hot weather.
Do close monitoring of pests, which can build up large populations during the summer. Growing these over the winter, as we do, we have not had many pest problems. Flea beetles sometimes, once the weather starts to warm.
Our mizuna schedule
On September 24 we sow these little crops in our outdoor nursery seedbed, which is covered with insect netting on hoops. We sow 7.5′, with roughly equal amounts of Green Mizuna, Golden Frills, and Ruby Streaks or Scarlet Frills. Red Rain is another we like. We are aiming for about 75 transplants on October 20. We transplant them 8″ apart with 6 rows in a 4′ bed. This takes 8′ length of a bed. This first planting will feed us from November 27 to January 25, with light harvests possible from November 5, and flowers and sprouting shoots as late as February 10.
Our second planting is direct sown in the hoophouse on November 9. We sow 6 rows about 6′ long (depending on available space). We thin these into salad mixes several times as they grow, increasing the spacing until they are about 6-10″ apart. After that we harvest by cutting off the larger leaves, sometimes individually, sometimes by “buzz-cutting” (snipping off leaves on one half of the plant an inch (25 mm) above the ground). Leaving half of the leaves growing seems to help the new leaves grow faster. Next time we harvest, we cut the other side. This planting provides harvests from February 26 to March 24 – just one month, although we get the thinnings from January 20, and the flowers and bolting shoots until mid-April.
A couple of years ago we added in a third planting, because we had some open space in the hoophouse. It follows the first Yukina Savoy. I wrote about some differences between the OP Yukina Savoy and the hybrid Koji. Perhaps Koji is less bolt-resistant than the OP. Late January brings it to an end.
We sow this third planting on February 1 and harvest it for a month from March 24 to April 23. This year this third planting is bolting April 15. (We have had a lot of temperature reversals this spring, which encourage bolting in brassicas.) Scarlet Frills and Golden Frills bolt later than Ruby Streaks and Green Mizuna. The timing of harvest fits perfectly with the second planting. We have sown it as late as March 3 and harvested April 10-April 30 (only 3 weeks when we sow that late).
Kitazawa Seeds sell 18 baby leaf mustards, including four red, purple or streaked mizunas. The other 14 are B. juncea, although a few don’t say. Most are frilly or ferny, a few merely wavy. Something for everyone.
Fedco lists theirs under “Asian greens”. Scroll down past Mizuna to Mustards to find several interesting gene pool offerings such as Pink Lettucy Mustard (Variations of greens with pink or purple pigments in midribs) for those seeking milder flavors; and the medium hot Purple Rapa Mix Gene Pool (sold out as I write this): Very vigorous tall serrated green leaves with purple veins and shading.
This is my twelfth and last Asian Greens of the Month series. You can see the others here:
I wrote about outdoor Yukina Savoy going into the winter, in my October post. Re-read that to get details of days to maturity, cold-tolerance (10F/-12C outdoors) and the differences between the open-pollinated Yukina Savoy and hybrids such as Koji. Five months after that posting we are harvesting the last of the over-wintered Yukina Savoy in the hoophouse. For us, this is a cooking green, not a salad crop. It’s delicious and easy to cook. A little robust for salads, for most people.
In March we are starting our hoophouse crop transition to early summer crops (tomatoes, peppers, squash, cucumbers) and meanwhile we are enjoying harvests of arugula, brassica salad mix, Bulls Blood beet greens, chard for salad and cooking greens, Russian kales, leaf lettuce, lettuce heads, baby lettuce mix, mizuna and frilly mustards, radishes, scallions, senposai, spinach, tatsoi, turnips and greens and yukina savoy.
We do two hoophouse plantings of Yukina Savoy: the first transplanted from outdoors on October 6, feeds us from December 5 to January 31. The second, transplanted from outdoors on October 24, feeds us from January 8 to early March, sometimes to mid-March. This spring several crops are bolting earlier than hoped-for! We have had some back-and-forth temperatures, which can trigger bolting. Among brassicas, Yukina Savoy is relatively heat-tolerant. This is part of why we do the second planting – it helps us extend the brassica season until we can harvest more outdoor kale.
We transplant Yukina Savoy at 12″ (30 cm) apart in the row, with 4 rows to a 4′ (1.2 m) bed. For a hundred people with lots of other vegetables available, we plant 60 in the first planting and 40 in the second. There are too many other crops competing for space in late October for us to plant more than 40.
Initially we harvest this crop by the leaf, until we see the stems start to elongate prior to bolting, when we cut the whole plant. (It is a loose head type of crop, so don’t wait for a firm head to form!) Actually we pull first, then cut off the head, then bang two roots together to shed the soil, and put the pulled root stumps on the bed to dry out and die. This is easier than cutting first and pulling later. If they do bolt before we get round to pulling them, I have added the pretty yellow flowers to the salad mix. Like all other brassica flowers, these are edible.
Kitazawa Seeds tells us that Yukina Savoy is a Brassica rapa Pekinensis group, for those with a love of brassica botany and those saving seeds. Also those, like us, looking for nematode-resistant vegetables. Brassica juncea are the most resistant brassicas. Kitazawa classifies it as a loose head type of Chinese cabbage.
Tatsoi is a very cold-hardy green (down to 10°F, –12°C), one of the ones we grow in our hoophouse to feed us after the winter solstice, when the crops have started to be fewer in number and each is less abundant in production rate. We have also grown this one outdoors in the fall for early winter eating, but no longer do this as the rate of growth inside the hoophouse is much better. In the fall tatsoi will not bolt, but in late winter/early spring it will.
I have been writing about a particular Asian green once a month since last May. To find the other articles, click the category “Asian Greens”.
Like Asian greens in general, tatsoi is a great crop for filling out winter CSA bags or market booths, and ultimately, dinner tables. Because the Asian greens are so varied in color, texture, shape and spiciness, you can add a lot of diversity to your crops by growing a selection that is easy to grow and can all be treated the same way. They are as easy to grow as kale. They germinate at a wide range of temperatures and make fast growth (much faster than lettuce in cold weather!)
Botanically, tatsoi is Brassica rapa var. narinosa, cousin of other turnip family greens such as Chinese cabbage, Tokyo Bekana, pak choy, mizuna and komatsuna. It is a more distant cousin of the Brassica oleracea greens such as Vates kale, Chinese kale and kai-lan, and of crops in the Chinese Mustard family, Brassica juncea (the frilly mustards like Ruby Streaks and Golden Frills).
Tatsoi is a relatively small plant with shiny, dark green spoon-shaped leaves and green-white stems. If given plenty of space it grows as a flat rosette, but if crowded it takes on a flowerpot shape. For sale, the whole plants are cut and the leaves banded together, so crowding them does not at all make them less marketable. It has a pleasant mild flavor.
We direct sow and then thin into salad mixes, leaving some to mature at 10″ (25 cm) across for cooking greens. You can also transplant at 3-4 weeks of age in the fall, at 6″ (15 cm) apart. Although we transplant most of our brassicas, to allow the beds more time without this crop family (which we grow lots of), we direct sow this one, which will have many plants in a small space.
Tatsoi has similar care requirements to other brassicas. Very fertile soils grow the best Asian greens, so turn in leguminous cover crops or compost to provide adequate nutrition. Asian greens are shallow rooted – Pay extra attention to providing enough water to prevent bitter flavors and excess pungency. Expect to provide 1” (2.5 cm) of water per week in cooler weather, 2” (5 cm) during very hot weather.
Do close monitoring for pests, which can build up large populations during late summer. We do nothing special for our tatsoi, but if you have a lot of brassica flea beetles or uncontrolled caterpillars, cover the sowings or new transplants with insect netting such as ProtekNet.
If you are growing tatsoi outdoors in late fall, you could use rowcover to keep your plants alive longer into the winter.
For our hoophouse, we make a first sowing of tatsoi in the very first bed we prepare for winter crops, on 9/6. We make a second sowing in mid-November. The first sowing will feed us for two months, November and December. The second sowing will feed us for a much shorter period of time: the second half of February, first week of March. It would bolt if we tried to keep it any longer.
It is entirely possible to make sowings between 9/6 and 11/15, and get harvests that last longer than our 11/15 sowing. The only reason we don’t is that we have so many other crops we love.
Tatsoi takes 21 days to be big enough for baby salads; 45 days for cooking size.
To harvest, initially we thin the rows to 1″ (2.5 cm), using baby plants in salad mix. Our first sowing provides thinnings from 10/8, one month after sowing. Next we thin to 3″ (7.5 cm), using these also for salad. Our next thinning, to 6″ (15 cm) gives us small plants for cooking. After this, we harvest individual leaves for salad or cooking. The second sowing provides thinnings 12/27-1/21 approximately.
Once we get close to the time the plants would bolt, we pull up whole plants and use them for cooking. We pull the most crowded plants first, giving the others time to grow bigger – they can grow as big as 12″ (30 cm) across. Overcrowding can lead to early bolting.
Overview of Winter Hoophouse Greens
In the big scheme of things, we harvest Tokyo Bekana and Maruba Santoh for heads in December, along with our first tatsoi; our first Yukina Savoy, our Chinese cabbage and Pak Choy in January, our second tatsoi and Yukina Savoy in February and early March.
Non-heading leafy greens such as Senposai, spinach and chard feed us all winter until mid-March when we need the hoophouse space for spring crops. (Read more about Yukina Savoy here in March.)
We clear our first tatsoi by 1/14, and use the space to sow our fifth spinach on 1/15. This planting of spinach is to be used as bare root transplants outdoors in March. Our second tatsoi is cleared 3/12 to prepare the space for early summer crops like tomatoes, peppers, beans, squash and cucumbers.
Sorry for the delay this week – technical problems.
If you have Chinese cabbage in your hoophouse, January is the month to harvest it in zone 7. We do not harvest leaves from this crop, but wait for it to form full-size heads and then harvest those mature plants. We sometimes start harvesting as early as December 4, if the plants have reached full size and we “need” to harvest them. Otherwise we wait till December 15. If we have planted enough we can harvest until January 23, or sometimes as late as February 9.
Chinese cabbage has very tender, light green savoyed leaves and is excellent for stir-fries, or pickling (sauerkraut or kimchee).
Chinese cabbage (both the Napa kind and the Michihli or Michihili kind) are Wong Bok types (Brassica rapa var. pekinensis) along with the “celery cabbages” – the non-heading Tokyo Bekana and Maruba Santoh.
We like Blues, an open-pollinated “barrel-shaped” Napa cabbage, shown in the photo above. Kasumi has the best bolt tolerance and is larger: 5 lb (2.3 kg) compared to 4 lb (1.8 kg); Orange Queen is a colorful but slower-growing variety (80 days in spring).
The Michihili types are taller and narrower, can be transplanted closer (8″) and might make more sense in terms of space use, although Napa cabbages do store better under refrigeration than michihli types. Jade Pagoda and the O-P Michihli both take 72 days from sowing to harvest in spring – considerably slower than Napa types. Michihili are more stress tolerant and resistant to bolting and black speck than Napa cabbage.
Blues takes 52 days from sowing to harvest in spring, but of course, takes longer in fall and winter. We sow September 15 in an outdoor nursery seedbed, and transplant into our hoophouse at 2-3 weeks old (October 2). It is very fast-growing in those temperatures and conditions. If we start harvesting December 15, it’s 3 calendar months from sowing, 91 days. The minimum germination soil temperature for Chinese cabbage is 50F (10C), and the ideal soil temperatures are 68F (20C) to 86F (30C). Under the ideal conditions the seedlings will emerge in 4 days. The maximum soil temperature to get any germination is 95F (35C).
We plant 52 plants for 100 people, with 4 staggered rows in the 4ft bed, 10.5″ apart (every 7th tine on Johnny’s row marker rake) and plants 10″ apart. With a harvest period of 5-8 weeks, 6-10 heads per week is about right for us.
We have not had many disease or pest problems with our hoophouse Chines cabbage. We do pay attention to using insect netting over the outdoor seedbed in the fall, but once we transplant indoors, our pest troubles are usually over. Vegetable weevil larvae have caused trouble in January. They come out of the soil at night and make holes in the leaves. They tend to prefer pak choy and turnips. We have used Spinosad against them with some success.
Tipburn (brown leaf margins, including internal leaves) is caused by quick drying of the soil, when the weather makes a sudden switch to bright and sunny from overcast. Be ready to irrigate when the weather suddenly brightens.
The winter-kill temperature of Chinese cabbage outdoors without protection is 25F (-4C). Our hoophouse crop has taken outdoor temps of 8F without inner rowcovers, and -8F with added thick rowcover. It is more cold-hardy than most varieties of pak choy, and less cold-hardy than Komatsuna, Senposai, tatsoi, Yukina savoy. Mizuna, Maruba Santoh and Tokyo Bekana have a similar level of cold-tolerance.
Once past the winter solstice, the order of bolting of Asian greens is something like: Tokyo Bekana and Maruba Santoh, pak choy, Chinese cabbage, tatsoi, Komatsuna, Senposai, mizuna, Yukina Savoy, leaf radish, frilly mustards.
When it’s time to harvest, we lever and pull the plant out of the soil, then cut off the root. This helps with the next task of replanting the space. It is much easier than cutting the plants at the base and then digging up the root.
After the Chinese cabbage are all cleared, we might follow with kale or collards on January 24 to transplant outdoors as bare root transplants in March. If we have no plans for a follow-on crop that early in the year, we fill gaps in the Chinese cabbage plot until January 25, using “filler” Asian greens we sowed in October. After that date we fill all gaps with spinach transplants until February 20, and from then on we only fill gaps on the edges of beds, leaving the bed centers free for tomatoes, etc in mid-March.
Grow Your Own Chinese Vegetables, Geri Harrington, 1984, Garden Way Publishing. Includes the names for these crops in different cultures.
Growing Unusual Vegetables, Simon Hickmott, 2006, Eco-Logic books, UK.
Oriental Vegetables: The Complete Guide for the Garden and Kitchen, Joy Larkham, revised edition 2008, Kodansha, USA
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), Stokes, Hudson 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.
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.
“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.
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.
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.
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.
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.