Oriental Greens

The Oriental leaves are leafy, cool season vegetables that thrive in Britain’s temperate springs and summers and overwinter quite contentedly in a tunnel or greenhouse. They are adaptable crops that grow well either in the ground or containers.

Group shot of harvested Oriental leaves.

Some types of Oriental leaves form loose-leaved rosettes while others produce tightly-packed heads. They can be harvested one at a time as individual plants when they reach full size or managed as a cut-and-come-again crop for multiple harvests. Either way, the leaves are excellent in salads and stir fries.

Oriental leaves are versatile in their propagation requirements. When weather conditions are favourable, they can be sown directly into the ground or a container filled with compost. Alternatively, the seeds can be sown in module trays and the seedlings transplanted after their roots fill the cells.

Sowing seed of yukina into modules

Yukina plant raised in modules ready for transplanting

Germination is seldom a problem. Sown no deeper than 5–6mm, seeds are quick to germinate and produce seedlings. Plants can be spaced about 30cm apart for the production of full-sized heads, or brought closer together for cut-and-come-again crops.

Transplanting modules of Oriental leaves outdoors

Like any leafy vegetable, all Oriental leaves eventually bolt, bringing leaf production to a halt. To help delay this for as long as possible choose bolt resistant varieties, avoid sowing dates that mean young plants are exposed to cold weather and keep the plants well-watered.

Bolted stem of tat soi

To guarantee a continuous supply of leaves several sowings should be made throughout the year. Sow directly outdoors only in late spring when the weather warms up, i.e. June or later. Earlier sowings of bolt resistant varieties can be tried in May – or even April in more favourable locations – though it might be wise to sow the seeds first in modules in a tunnel or greenhouse, where conditions are likely to be warmer. The last sowings for outdoor crops can be made sometime in August.

Mizuna leaves grown overwinter: left grown in tunnel, right grown outdoors

Plants can be overwintered in a tunnel or greenhouse. To get the best yields seed should be sown into modules in September and the seedlings transplanted in October, after the summer crop – tomatoes, cucumbers, peppers, etc. – has been cleared. Barring a mid-winter slump due to cold temperatures, the plants should continue growing until March or so, at which point they will bolt.

Growing Oriental leaves in tunnel over winter: growing crop (with snow on the plastic); clearing the bolted crop in the spring.

Seed of Oriental leaves can be sown at any time throughout the winter. However, no matter when they are sown the plants will bolt at the same time in the spring. This means the later a crop is sown, the smaller the harvestable yield, and crops sown after Christmas are best for cut-and-come-again harvesting as they are unlikely to form full heads before bolting occurs.

Types of Oriental leaves

Oriental leaves display noticeable differences in texture and flavour, so it is worth growing a selection and using them either individually or mixed together in salads and stir fries.

Chinese cabbage: Chinese cabbages are faster growing than typical British cabbages. They are mild flavoured and light green, and their leaves can be either tightly packed into a head or formed into a rosette of loose leaves. So far, Sea Spring Seeds sells only the headed type.

Pak choi (also called pac choi and bok choi): The plants of pak choi develop into upright, heavy bunches of large green leaves that have thick, crunchy midribs, either white or light green in colour.

Tatsoi (including Yukina Savoy): Tatsoi is sometimes called rosette pak choi because the plants develop into rosettes of dark green spoon-shaped leaves with fairly thick petioles.

Mizuna: Mizuna produces dark green, deeply cut leaves with thin, white petioles It may be more bolt resistant than other varieties of Oriental leaves.

Problems

Oriental leaves are susceptible to both pests and diseases that can severely reduce both yield and quality. Fleece or netting will help control some of the pests, while good crop management will alleviate even the most serious diseases.

• Pigeons, rabbits and deer

Voracious eaters that can devastate a crop. Fleece or netting draped over the plants will effectively control the problem.

• Snails and slugs

Ubiquitous pests that can kill young seedlings and transplants. They can be controlled by pellets, parasitic nematodes (for slugs, but not snails), and nightly collection trips to the garden. For more information, check out the following websites of the Royal Horticultural Society:

Slugs: http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=228

Snails: http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=231

Chinese cabbage with slug and snail damage on its leaves

• Whitefly

Small white insects that fly up in clouds when the plants are disturbed. They suck the sap from the leaves, leaving a sticky excretion and a black sooty mould that thrives on it. For more information see: http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=482

• Flea beetles

Small, shiny beetles that leap from plant to plant, nibbling holes in the leaves. Covering the plants with fleece or fine netting will help control an attack. For more information, check out the following websites: http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=510 www.which.co.uk/documents/pdf/flea-beetles-151778.pdf

• Cabbage caterpillars

Creeping crawlies that can strip leaves almost bare. Non-chemical control is easy: cover the plants with netting or fleece, rub off the eggs, and pick off the young caterpillars. The following website provides more information: http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=457

• Mealy cabbage aphids

Grey sucking insects found on the underside of leaves. Cover the plants with fleece or netting to prevent an attack, squash by hand in the case of light infestations, and spray with an approved insecticide if they have become well-established. For more information, see the following: http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=181

• Cabbage root fly

Grubs in the ground feed on the roots, stunting growth and, in extreme cases, killing the plants. Physical barriers such as netting and fleece provide excellent control of this pernicious pest. Further information is at the following website: http://www.which.co.uk/documents/pdf/cabbage-root-fly-151755.pdf

• Downy mildew

A fungus disease causing yellow patches on the upper side of the leaves and a fuzzy growth underneath. For causes and control, check out the following: http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=105

• Club root

A root disease that can persist for up to 20 years in the soil. Because of its seriousness, carefully read the information found at the following websites: http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=128 www.which.co.uk/documents/pdf/clubroot-151769.pdf