December 2009 - Asian Vegetables

Article Courtesy of
The National Garden Bureau

Photos Courtesy
The National Garden Bureau

ASIAN EGGPLANT

History & Classification

Eggplants have been grown in China and India since the fifth century. In the twelfth century, the Arabs introduced them into Spain where they became popular as an aphrodisiac. They moved into England and Italy in the 16th century as ornamental plants only since they were thought to cause madness if consumed. Their popularity in all areas of the world today is evident by the hundreds of cultivars available. Asian eggplants have smaller fruits on smaller plants than traditional Italian and American types. The glossy black, white, lavender, pink, purple or green fruits are long and slender, usually about two inches in diameter and up to nine inches long.

Asian eggplants, Solanum melongena var. esculentum, belong to the nightshade family, Solanaceae, along with peppers, tomatoes and potatoes. They are called nasu in Japan.

Site planning, preparation and sowing seed

Choose a site in full sun. Eggplants will thrive as long as the soil is well drained. This is so important that in heavy soil, they should be grown in raised beds. Eggplants also need rich soil, especially in potassium. The addition of copious amounts of organic matter will make the soil rich and moisture retentive.

Eggplants must have warm soil to grow well and they take a long time to reach maturity. The best method in northern climates is to grow from seed indoors or purchase bedding plants and plant them outdoors when the soil is thoroughly warm. Start seeds indoors 10-12 weeks before the last frost. Plant them outdoors after hardening them off and after all danger of frost is past.

Growing on

Transplant eggplants 18-24 inches apart in rows 30 to 36 inches apart . For intensive or raised bed gardens, allow 24 inches in all directions. Eggplants grow best in hot weather. Eggplants are heavy feeders, so in addition to providing rich soil initially, feed them with composted manure or a balanced fertilizer when the plants are half grown and again after harvesting the first fruits. Mulch the plants lightly after the soil is warm. Eggplants are tolerant of dry conditions, but produce much better if well-watered during dry spells.

As the plants begin to bloom, pick off the first few flowers to force the plant to put energy into more fruit. Some gardeners stake and prune Asian eggplants like tomatoes to keep the fruits straight and long. Keep an eye out for signs of flea beetle damage or yellowing bottom leaves which may indicate verticillium wilt. The easiest way to control flea beetles is to grow the plants under row covers until they begin to bloom. If you suspect verticillium wilt, remove the entire plant and destroy it to prevent the disease from being transferred to other plants. Always rotate crops and don't grow eggplants where you've grown any other nightshade plant for three years.

Harvest & Storage

Harvest usually begins in mid to late summer, about 70-90 days after sowing the seeds. Harvest when the fruits are about six inches long and the skin is glossy and firm. If it begins to lose its gloss, the fruit is past its prime and may become bitter. Discard fruits that turn brown or feel spongy instead of firm. Harvest eggplants with pruning shears or a knife to avoid tearing the plant. Eggplants do not store well, so eat them as soon as possible after picking; they can be refrigerated for a few days. The easiest way to store an abundant crop is to cook them into a favorite dish and freeze the dish. They don't freeze well by themselves.

Eating qualities

Asian eggplants are milder and more delicate in flavor compared to American and Italian types, although many feel they have more "eggplant" flavor. They have very tender skin so there is no need to peel them. They are flavorful grilled, fried, roasted, pickled or stir fried.

Asparagus Bean

ASPARAGUS BEAN

History, definition & classification

The asparagus or yardlong bean originated in southern Asia and is now grown extensively in Asia, Europe, and most recently, the United States. These unique beans grow on twining, delicate stems with a tenacious root system. The plants bloom in mid-summer with a pair of large white or purple flowers. Once pollinated, the flowers are followed by tiny dark green beans that reach a foot long in only a few days. The beans can grow up to three feet long, ripening to pale green and inflating as the red or black seeds ripen.

Although they resemble pole snap beans (Phaseolus vulgaris), asparagus beans are more closely related to southern cowpeas, Vigna unguiculata. Asparagus bean, Vigna unguiculata subsp. sesquipedalis, is called dow gauk in China, sasage in Japan, and Chinese long bean or yardlong bean in Europe and the United States.

Site planning and preparation

Asparagus beans thrive in average garden soil that is loose and friable. Rich garden soil heavy in nitrogen causes abundant leaf growth and few beans. True legumes, they enrich their soil by trapping atmospheric nitrogen in nodules on their roots. With the help of nitrogen fixing bacteria, the plant makes its own food. Choose a site in full sun and loosen the soil to a depth of eight to ten inches in preparation for sowing. Mix in compost or composted manure in spring to boost soil fertility slightly. These climbing beans must be grown on a trellising system. Bamboo tripods or row trellising with poles and string are effective. Whichever method you use, make it at least seven feet high to accommodate the vines.

Sowing seed & growing on

Asparagus beans thrive in heat and wither in cold, so sow after all danger of frost has passed and the soil has warmed. Usual timing is to sow them about two weeks after sowing green beans. To move the schedule ahead, you can put down a black plastic mulch to warm soil earlier. If using a tripod system, plant three or four seeds to each pole. If using a row trellis, plant the seeds 3 to 4 inches apart in rows 8 inches apart. Plant the seeds two inches deep in good soil or an inch deep in heavy soil. If you have a very long growing season, make two more successive sowings, at two-week intervals. In northern climates, a single sowing in late spring will often produce until frost.

Asparagus beans germinate in about a week and will begin producing abundantly once the weather heats up. They easily tolerate hot weather and even some drought. However, to keep the beans producing, water in dry spells. It is unnecessary to fertilize asparagus beans unless you have nutrient-poor soil.

Harvest, storage & eating qualities

You should have harvestable beans about two months after sowing, continuing throughout summer and into the fall. Harvest when the beans are about half the diameter of a pencil, before the seeds have filled out inside and when they still snap when bent. You may need to harvest daily since continuous picking keeps the plants producing. The plants will stop producing if beans are left to ripen. Although the beans will keep several days in the refrigerator, they are best eaten soon after harvesting. They can also be blanched and frozen for winter storage.

Asparagus beans get their common name from a taste similar to asparagus. They have a more dense texture than snap beans and more intense "bean" flavor. Their texture and flavor hold up well when stir-fried or steamed. If the beans are left to mature somewhat, they can be shelled and cooked as other southern "peas" .


Daikon	Daikon	Daikon

DAIKON

History & classification

There are literary references and archaeological remains of winter radishes in ancient China. Daikon is the Japanese name for the radish that is so popular in Asian cuisine. Daikons are long and narrow and usually white, green or creamy yellow. They range from two to three inches in diameter, and from six to fifteen inches long, round is also common. Daikons belong to the species Raphanus sativus var. longipinnatus, along with other types of winter radish.

Site planning, preparation & sowing seed

Daikons, a root crop, must have nutritious soil for good development or they become woody and strong-flavored from slow development. Loose, deep and friable soil allows the long roots to develop unhindered. Choose a spot in full sun for the best development.

Daikons are a cool season crop that is harvested in spring or fall. There are heat tolerant varieties that will grow during summer. In northern gardens, sow in early spring or late summer. In southern gardens, sow about two months before the last frost so the roots will be ready for harvest in late spring. Sow seeds about 1/4 to 1/2 inch deep in rows 12-24 inches apart. Thin seedlings to 8-12 inches apart. If gardening intensively or in raised beds, thin the plants to 8 inches apart in all directions.

Growing on

Thinning the plants to the correct spacing is absolutely critical to develop healthy roots. Keep the plants well-watered in dry times to keep the roots tender. Fertilize four weeks after planting with a high phosphate, high potash fertilizer. Avoid high nitrogen which develops leaves at the expense of roots. Watch for root maggots, especially if you've grown carrots, cole crops or radishes in the area in years past. A sprinkling of wood ashes around the plants will help curb the damage.

Harvest & Storage

Daikons are ready for harvest 50-60 days after sowing. They can remain in the ground after they mature, but the longer they stay, the more pithy they get. It's best to harvest all of the plants and store them for use. When harvesting, dig carefully with a spading fork to avoid harming the roots. It is especially important to avoid injury if you plan to store the plants. Daikons will store for several months in a refrigerator, root cellar or cool basement in damp sand. If you don't have good storage conditions, you can blanch and freeze them.

Eating qualities

The daikon flavor varies from mild to pungent, and all types are crisp, much like turnips. Peel and slice them raw to serve with dips or in salads, boil or steam and serve them like cooked turnips, or grate them into a stir-fry. Daikon greens are tasty when picked young and sautéed like turnip greens.

Bok Choi

PAK CHOI (pak-choy) (or Bok Choi)

History & classification

Pak choi is native to eastern Asia where it has been grown for thousands of years. The Celts brought the vegetable to the British Isles, and it became popular in Europe until the late 1800s and then in the United States since 1900. The plant is grown for its thick white tender stalks that are the petioles and main veins of the leaves. The leaves are dark, glossy green with white veins. There is also a miniature green variety with green tender stems.

Brassica rapa (Chinensis group), called celery cabbage, Chinese celery and Chinese mustard cabbage, is more closely related to mustard than cabbage. The Cantonese name is bok choy or pak choi and the Mandarin name is pe-tsai or pei tsai. The name means white vegetable in Chinese. Pak choi is a member of the mustard family, Brassicaceae, to which cabbage, mustard, broccoli, kohlrabi and turnips belong.

Site planning and preparation

Pak choi performs best in full sun in a somewhat cool spot. Provide rich, loose soil that is very well-drained to prevent crown rot. Incorporate plenty of well-rotted manure or other organic matter into the planting bed to help retain moisture. If the bed is low enough to be poorly drained, raise it, but not more than 6 inches to prevent the soil from becoming too warm.

Sowing seed

Plant pak choi in very early spring and again in mid to late summer for the fall garden. In cool climates, sow seeds 1/4 - 1/2 inch deep directly in the garden after the danger of frost has passed. Sow the seeds three to four inches apart and then thin to 8-12 inches apart. In climates with hot summers, start the plants indoors six to eight weeks before the last frost. Start them in individual pots to avoid damaging the roots in transplanting. Transplant outdoors two to three weeks before the frost-free date. Plant in rows two to two and a half feet apart or space them a foot apart in raised beds or intensive gardens. For fall planting, sow the seeds directly about 3-4 inches apart and thin to 8-12 inches once the seedlings are up. The plants can be grown in a cold frame to extend the season.

Growing on

Pak choi is a heavy feeder, so fertilize with composted manure or a balanced fertilizer four weeks after setting out transplants. Take precautions against cabbage worms, cabbage root maggots and flea beetles. The plants can be grown under row covers to keep the pests out, or sprayed regularly with Bacillus thuringiensis to prevent worm damage. Some gardeners have luck keeping flea beetles at bay by alternating rows of pak choi with garlic and green onions.

Harvest & Storage

Pak choi greens can be used as early as 30 days after sowing; it takes about 50-60 days to have harvestable heads. Harvest the outer leaves while they are tender early in season. As the weather heats up, harvest the tender inner leaves. You can also cut the whole head, which will weigh 3-4 pounds. Pak choi is a short-season vegetable so it tends to bolt quickly. Breeders are developing types that take much longer to bolt, but pak choi is a cool-season vegetable so it sends up a flowering stalk as soon as the weather gets warm. A flower stalk usually indicates that the stalks and leaves are getting tough. Pak choi keeps several weeks in the refrigerator or for a week or so in a cool cellar. If you have a cold frame, dig the plants with the roots on, place them in the cold frame and cover them with straw and dirt. They will keep several months this way.

Eating qualities

The stalks of pak choi are not fibrous even though the plant is sometimes called celery cabbage. They are tender, and particularly good when cooked lightly in a stir-fry. Pak choi is a stock ingredient in many Chinese recipes. While tender, the stalks can be shredded and added to cole slaw with other types of cabbage. The leaves are good when prepared like other greens, and the thinned seedlings are superb when lightly sautéed. Pak choi can be blanched and frozen to add to soups and stews.

Snow Peas

SNOW PEAS

History, areas of origin & classification

Snow peas originated in the Mediterranean, and were grown widely in England and Europe in the nineteenth century. They were called English sugar peas or mangetout in France. The Chinese adopted these peas into their own cuisine from the English, and they have been known as Chinese snow peas ever since. Snow peas have light green pods that follow purple or white, sweetly scented flowers. Some varieties climb with twining tendrils to four or five feet, and other varieties are dwarf types, only growing to two or three feet. Snow peas are true legumes, classified as Pisum sativum var. macrocarpon.

Site planning and preparation

Snow peas need soil that is rich in phosphorus and potassium. If your soil is somewhat acidic, add wood ashes or ground limestone. Otherwise, add a fertilizer high in phosphate and potash. There is no need for extra nitrogen since the plants fix atmospheric nitrogen. Snow peas perform best in soil with plenty of organic matter which makes the soil moisture-retentive. Select a site in full sun and rotate peas annually to avoid blights and root rot. All snow peas need some sort of trellising, even the dwarf varieties. They have fairly weak root systems and untrellised peas don't produce as well as those on a sturdy trellis. A lightweight trellis of netting or string is sufficient as long as it is securely anchored. Some gardeners use shrubby branches to make a natural trellis.

Sowing seed

Snow peas should be grown as an early spring or fall crop in areas with hot summers. In areas with mild winters, they are usually grown as a winter and early spring crop. Make successive sowings every ten days from March through May for harvest through early July. Some gardeners soak pea seeds for 24 hours or sprout them before planting to give them a head start in the cold ground. It is wise to dust the seeds with a bacterial inoculant to help boost their nitrogen-fixing capacity. Plant when the soil temperature reaches 45 degrees and the soil is dry enough to till. Plant the seeds one to two inches deep in prepared soil, two to three inches apart in rows 18-24 inches apart. Be sure to put your trellising system in place when you sow the seeds to avoid disturbing the tender roots later.

Growing on

Keep snow peas well-watered during dry spells and cultivate lightly between the rows to remove weeds. Don't cultivate too near the peas, however, because their roots are extremely vulnerable. Apply mulch as the soil warms in order to keep it cool. As soon as the peas have finished bearing, turn them under rather than pulling them. This provides nitrogen to other crops. Watch for fusarium and root-rot diseases. Fusarium wilt, a vascular disease, can usually be avoided by rotating your crops. Avoid root rot by not planting your peas too early.

Harvest & Storage

Snow peas are ready to harvest 50-60 days from sowing. Pick them when tiny peas are just beginning to swell inside their pods, usually 5-7 days after flowering. Harvest as long as the peas are very small inside, daily to keep plants producing. If not picked regularly, snow pea plants will stop producing. They also stop producing as soon as the weather gets hot. When you see production begin to slow, be ready to pull the plants or dig them under. Try to eat or blanch and freeze your snow peas as quickly as possible after picking. Although they can be kept in the refrigerator up to two weeks, they tend to lose their intense sweetness.

Eating qualities

The sweet, crisp, tender pods are eaten whole, either raw or lightly steamed or sautéed. The pods lack the papery inner membrane of regular peas, which is why they are so tender. The tender shoots (called Dow miu) and leaf buds are considered a delicacy in China.

The National Garden Bureau recognizes the experts who reviewed the text and offered their advice growing these crops. They are Ms. Yukie Benech, American Takii and Mr. Joe Kojima of Sakata Seed America.