WANT A REALLY productive garden? Try growing a few Asian vegetables! They are easy to grow, they taste really good and they're very nutritious. Many come from the large Brassica family, which also includes the familiar cabbage, cauliflower, kale, radish and the mustards. I predict that once you get past Asian vegetables' unfamiliar names, you will find several favorites that you will want to grow every year.
Top of my list is Tokyo bekana. It looks like a looseleaf lettuce, with crinkled pale green leaves, but it grows faster and tolerates more heat than lettuce. It is what we call a cut-and- come-again crop, because you can harvest it three or four times from one planting. It can be eaten raw or lightly cooked.
Mizuna is often found in salad mixes, and it is a good substitute for similar-tasting arugula. The feathery leaves (which can be green or purple) get more peppery as they mature, but cut at the baby-leaf stage they are very mild. Another mild mustard green is tatsoi, which has lovely rounded dark green leaves that grow in a small rosette.
Bok choy, sometimes called pak choi, is better known, with its thick white stems and dark green leaves. Raw, steamed or stir-fried, it deserves its popularity, and baby bok choy is a treat. (Choy, or choi, just means cabbage or vegetable, by the way.) Equally well known now is napa cabbage, also marketed as michihli, tientsin, or Chinese cabbage. Its tightly packed savoyed leaves are great stir fried or in coleslaw, and I pickle it to make kimchi.
There are several red and green mustards that, when mature and raw, pack a peppery punch that I enjoy, in moderation, in salads. Cooking makes them much milder. The seed can be collected and dried to make mustard condiment. Chrysanthemum greens, also known as shungiku, can be flat or serrated, and they have a pleasantly tangy taste that becomes bitter if they are over-cooked. The pale leaves turn dark green when cooked.
Komatsuna has slim white stems and dark green leaves. It can be harvested at any stage, and it is very heat tolerant. An attractive and unusual addition to salads is hon tsai tai, which produces lots of thin purple stems, with edible flowers and greens that can be harvested several times in a season.
The best-known Asian root vegetable is daikon, or Japanese radish. In the right soil, these giant white roots can reach 18 inches or more. It can be chopped or grated to be eaten raw, or pickled overnight in rice vinegar to make kimchi.
Soil preparation is fairly typical for leaf vegetables: well amended with mature compost, with good drainage and a pH between 6.0 and 6.5, which is slightly on the acidic side of pH neutral (7.0). Compost helps retain a consistent level of soil moisture, which these juicy, tender greens need. Make sure the NPK nutrients are adequate, particularly nitrogen.
Most Asian greens grow so quickly that direct seeding is easier than transplanting, although that is an option. Depending on the variety, and at what stage of growth you intend to harvest them, you can sow seeds in single rows or broad, dense bands.
For full-size heads, sow seeds about an inch apart and a quarter of an inch deep. I try to get the best of both worlds by thinning and eating young plants, leaving the rest to grow about three or four inches apart. At the baby stage, leaves are tender and mild. The larger varieties, such as napa or Chinese cabbage, need even more room, so they should grow about a foot apart. The thinnings are delicious raw or very lightly stearned. Some Asian greens— particularly the mustards—can get really spicy if allowed to grow to maturity, although cooking lessens their punch.
If a more-or-less continuous harvest of baby leaves is your plan, seed can be sown quite densely, up to about 40 seeds per foot, in bands 4 to 6 inches wide. The fast-growing, tender leaves are best kept dry to avoid rot, so drip irrigation is recommended for dense plantings. Water consistently and deeply, while allowing the soil surface to dry between waterings.
As with most tender greens, the cool weather of spring and fall are preferred. Even so, I grow Tokyo bekana and mizuna through the summer and (protected in a hoophouse) through the winter, too. Hot weather can make some varieties bolt, but you can turn that to your advantage by harvesting the attractive small flowers for salads, or letting them set seeds for you to save for next year's crop.
If you intentionally let them make seed, keep varieties well separated by as much as 100 feet or more, or they may cross. Even better, grow a single variety one year and something different during the following season. Pollinators, particularly tiny non-stinging wasps, love those spicy (to us, anyway) little yellow flowers. If they carry pollen from one variety to another, the seed you gather might grow into something that will surprise you.
Except for tatsoi and daikon, most Asian greens do well as cutand- come-again crops. Young leaves, even of the mustard varieties, are mild and tender. Harvest with a very sharp knife, cutting an inch or so above the soil. Even sharp scissors crush tender stems, so a carefully wielded sharp knife is better. Irrigate or fertilize the plants after each cutting to help them recover and regrow.
Ideally, harvest leaves by immersing them in ice-cold water as soon as they are cut. This will keep them crisp and increase their keeping qualities. Store slightly damp leaves in the refrigerator, in a plastic bag containing a dry paper towel.
Heads of bok choy are very fragile when they are harvested. Allow them to wilt slightly to minimize stem breakage, then cool them quickly and refrigerate them.
Several Asian greens, cooked and chopped, make a good substitute for spinach. Cook by steaming for no more than two or three minutes to retain nutrients. If you have more than you can eat fresh, blanch briefly in boiling water, then freeze airtight for later use.
Asian greens are rich in calcium and vitamins A, C and K.
Because most Asian greens are of the cabbage family, all the enemies of the Brassicaceae, including the cabbage butterfly, slugs and aphids, may attack them. In my experience, however, flea beetles are the biggest problem.
Be vigilant. When you see cabbage white butterflies skipping around your plants, don't doubt for a second that they are laying eggs. Look for tiny orange eggs on the undersides of leaves; squish them! If they hatch into small velvety green caterpillars (known as the imported cabbageworm) spray the plants thoroughly with Bt-k (Bacillus thuringiensis ssp. kurstaki). Repeat one week later. Be sure to get the kurstaki strain of Bt, because other strains will not work.
Slugs are everywhere, and they can turn cabbage and mustard family leaves into lacework overnight. Organic and nontoxic Sluggo works very well, and I have successfully used food-grade diatomaceous earth (not the kind used in pool filters). It is safe and effective.
Aphids are easily dealt with, using thorough sprays of Safer organic insecticidal soap. Douse the underside of leaves, as well as the tops. Drench the plants, and repeat one week later.
Flea beetles are a real pain. They riddle leaves with tiny shot holes that can weaken the plant if left uncontrolled, and their larvae attack root systems. They love mustards, Asian greens, arugula, spinach and other leafy plants. I have battled them every which way, from diatomaceous earth to neem oil, and I have yet to find anything that is as effective as floating rowcover fabric, installed immediately after sowing or planting, with tightly sealed edges.
Remember that flea beetles reproduce in the soil, and produce up to four generations a year. Even rowcovers are ineffective if there are larvae present in the soil where you plant, so rotate your crops— don't plant susceptible crops in the same place two years in a row. If you do get an infestation, rototill or cultivate the soil deeply to interrupt their life cycle.