This is the third installment in a series about my experiences growing Asian vegetables. You can find the other articles by clicking on the tag “Growing Asian Vegetables” at the bottom of this post.
In her book “Oriental Vegetables: The Complete Guide for the Gardening Cook”, Joy Larkcom says she is tempted to give komatsuna the ‘most underrated vegetable award’. I couldn’t agree more. This leafy, tasty relative of the turnip has quickly become one of my favorite greens. But up until a couple of years ago, I had never even heard of it.
This unassuming green is sometimes called Mustard Spinach, and the Japanese have likely grown it since ancient times. Modern taxonomists usually call it either Brassica rapa var. perviridis or B.r. var. komatsuna. It is considered a biennial, though first year plants can bloom if stressed.
It’s hardy enough to survive our zone 6b winters protected by a cold frame, usually without the slightest bit of damage. The freezing temps only seem to make it taste sweeter. And speaking of taste, komatsuna has a mild flavor somewhere between mustard and cabbage, not as strong tasting as its earthier turnip green cousins.
Seed can be sown in place where plants are to be grown, or started indoors like I usually do to get a jump on growing. Most varieties will get pretty big, from 12-18 inches tall, but growth is mostly upright so plants can be grown fairly close together if space is limited. The spacing will depend on how large you want the plants to grow. Sow or plant thickly for small plants (2-4” apart) or farther apart (6-12”) if you plan on letting the plants get larger. A 6” spacing works well for me, with plants getting about a foot tall and almost as wide. The fast-growing plants appreciate a fertile soil and plenty of moisture.
Flea beetles can be a problem, and sometimes caterpillars will munch on the leaves too. Floating row cover will keep both of those pests away, while Bt will also control the caterpillars. Iron phosphate pellets (like Sluggo) can be used to control slugs and snails.
There are several hybrid varieties of komatsuna available, including Summerfest and Torasan, as well as open-pollinated selections. There is also a red leafed hybrid available that was developed primarily for baby greens and salad mixes. Though Summerfest may be preferred for warm season plantings, it has also proven to be quite winter hardy here as well, so don’t let the name fool you.
Komatsuna has also been crossed with other brassicas to produce some unique varieties. Green Boy hybrid has long slender leaf stalks and is reported to be a cross between komatsuna and a green stem pak choi. Misome hybrids were created by crossing komatsuna with tatsoi. And Senposai hybrids are the result of a komatsuna cross with regular heading cabbage.
Like many other Asian greens, komatsuna can be used at any stage, from baby leaves on up to mature leaves that can be a foot or more long. Leaves can be harvested individually as needed, or the whole plant can be cut. The leaves will resprout from the roots after cutting, and usually at least two cuttings can be made before rejuvenating the soil and replanting is necessary.
The leaves can be cooked by all the methods usually used for Asian greens: steaming, stir-frying, boiling in a small amount of water, or added to soups. In Japan, leaves are also pickled. And the baby leaves can be eaten raw in salads.
If you are looking for an all-season green that is easy to grow, tasty, and nutritious, you might want to give komatsuna a try. Who knows, it may wind up being one of your favorite greens too. I’ll be back soon with the next installment highlighting another Asian vegetable. Until then, happy growing!