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.