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Oriental Greens

                  and mustards

Oriental leaves are leafy brassicas that thrive in Britain’s temperate climate. They are adaptable crops that grow well during the summer and autumn outdoors and in the spring and winter undercover. They are flexible in their cultural requirements, performing admirably whether grown in the ground or containers. The leaves can be harvested at virtually any size and are worthy companions in the kitchen, where they are equally adept in both salads and stir fries.

Group shot of oriental greens

Group shot of harvested oriental leaves.

Types of oriental leaves

Oriental leaves can be neatly divided into easily distinguished types that vary in texture, flavour, and growth habit:

  • 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 bunch of loose leaves. By far the most common is the headed type.

Chinese cabbage var. Apex

Chinese cabbage var. Apex.

  • Komatsuna: A robust grower that has fairly broad, dark green leaves with wide mid-ribs. The plants are large-sized and make an excellent substitute for both kale and spring cabbages. Fairly bolt resistant. The variety sold by Sea Spring Seeds is Torasan
  • Mibuna: Form bunches of elongated, excessively narrow leaves – they are almost grass-like in appearance. The variety sold by Sea Spring Seeds is Green Spray.
  • Mizuna: Plants produce dark green, deeply cut leaves with thin, white mid-ribs. Relatively slow to bolt. Sea Spring Seeds sells two mizuna varieties: Broadleaved and Red Knight.

MizunaMIZUNA

Broadleaved mizuna has wider leaf blades than many other mizuna varieties.

  • Mustard: Appreciated by British Asians, who use them both raw and cooked. They are distinctively strong-flavoured and have a fairly unrefined texture. Leaves can be quite tall and broad, though there are shorter varieties whose leaves are deeply cut and frilly. Plants have a tendency to bolt prematurely. Sea Spring Seeds sells three mustard varieties: Red Giant, Flaming Thrills and Golden Streaks.
  • Pak choi (also called pac choi and bok choi): The plants of pak choi develop into heavy, upright bunches of leaves with thick, crunchy mid-ribs that are either white or light green in colour. The variety Joi Choi, sold by Seed Spring Seeds, is particularly slow to bolt.

Pak choi var. Choi Joi

Joi Choi is a very bolt resistant variety

  • Tatsoi (including Yukina Savoy, sold by Sea Spring Seeds): Leaves are dark green and spoon-shaped with relatively thick mid-ribs. Tatsoi plants bolt quite quickly.

Yukina

Tatsoi var. Yukina Savoy.

  • Rocket. There are two types of rocket, salad rocket and wild rocket. Wild rocket is a smaller plant and tends to grow slower, but does have a very strong flavour. Salad rocket is a larger plant and does grow very fast. All rocket types bolt very quickly. Sea Spring Seeds sells Salad Rocket.

Sowing strategies

With good quality seed, germination is seldom a problem – simply sow the seed about 5 to 6mm deep. The seeds will germinate at temperatures that range from 10 to 30º C, with the optimum somewhere between the two extremes.

Oriental greens are remarkably well-adapted to different growing systems. For example, they can be grown in the ground or compost-filled containers such as growbags, pots and troughs. As an added bonus, crops are easily established by direct seeding, though in most cases, producing transplants in module trays works equally well (see below for details)

Providing warmth

Depending on the season, oriental greens can be grown either undercover or outdoors. Crops grown in the summer and early autumn – when the weather is still warm – are perfectly content outdoors. In contrast, spring and winter crops should be undercover, in an environment that:

  • Provides warmth to the growing plants. Oriental leaves like the warmth and should be grown undercover in the winter and spring, when it is cold outdoors.
  • Reduces the chances of bolting. As a general rule, Chinese cabbage and pak choi will bolt prematurely if the young plants are exposed to the cold. To reduce the risk of bolting, sowing seeds and growing young plants should be done under cover until the weather warms up.

To be honest, we’re not completely sure how the cold affects the young plants of the other oriental leaves. But to be on the safe side, we take a conservative approach and treat them – with a few exceptions – the same way as Chinese cabbage and pak choi.

Continuity of supply

The plants of oriental leaves will continuously produce new leaves until they bolt, at which point they turn reproductive and form flower stems. If you cannot do without your greens your greens, a single crop won’t satisfy your needs, and so for a regular supply of leaves make new sowings throughout the year.

The relationship between growing distances and harvest times

Oriental leaves can be harvested at virtually any size in their development, and before embarking on the cultivation of oriental leaves, you should have some idea at which stage of the crop’s development you wish to harvest. This has a direct effect on the spacing between plants – the bigger you want the plants, the more space they need between them.

Sowing, growing and harvesting

Oriental leaves are flexible in their cultivation requirements, and we give instructions for four ways to sow, grow and harvest them:

  1.  Single harvest of large-sized plants
  2.  Cut-and-grow-again for teenage leaves
  3. Cut-and-grow-again for baby leaves
  4. Easy Peasy Gardening for baby leaves

A note on sowing dates and plant spacings: The various types of oriental leaves differ slightly in their cultural requirements, including sowing dates and plant spacings. For the sake of clarity, however, the sowing dates and plant spacings given below are what we at Sea Spring Seeds consider to be a ‘good’ average across the range of oriental leaves. This means that compromises have been made and that the dates and spacings are not necessarily the optimum for each type. They are, nevertheless, good enough to produce bountiful harvests, though if you wish for more precision, please refer to Joy Larkcom’s book Oriental Vegetables. It’s an impressive work written by one of Britain’s most dependable and knowledgeable gardener writers.

 

1. Single harvest of large-sized plants

All oriental greens can be grown at a wide spacing and harvested when they become large-sized. Grow the plants either in the well-worked ground of your garden or in large, compost-filled containers such as trays, troughs and growbags. For the best results, the plants must not be overcrowded, so leave plenty of room around each one. One way to do this is to space the plants equidistant from each other, preferably in a triangular pattern. As a general rule of thumb, leave about 30cm each way.

Starting the plants

Plants are started from seed using two basic strategies:

Direct seeding: In this method, the seed are sown directly into either compost-filled containers or in the ground, where the plants are left to grow and develop. To start the plants, sow two or three seeds in each ‘post’. After germination, thin the seedlings down to leave one per post.

Started as transplants: This is a two-stage process that involves both sowing and transplanting. For the first stage, sow two or three seeds in each cell of a compost-filled module tray. After germination, thin the seedlings down to leave one in each cell. Keep the tray well-watered, and give a high-nitrogen liquid feed two or three weeks after sowing. For the second stage, transplant the young plants to their final spot when their roots fill the cells of the tray.

transplanting oriental greens

Transplanting modules of oriental leaves outdoors.

Sowing times

There are thee main sowing times, each of which needs to be handled differently to get the best crop:

For early crops: You should attempt growing an early crop only if your garden is in a mild part of Britain – otherwise, plants may bolt early due to the exposure of young plants to cold weather. To provide the requisite warmth, sow in May undercover, putting the plants outdoors only when the temperatures have increased – anytime from the beginning of June is about right. In practical terms, this means there are three options available to you:

  • Start transplants undercover in May, planting them outdoors – either in the ground or containers – in June when they are big enough.
  • Direct sow in the ground outdoors, covering the area with cloches or cold frames until June, when they can be removed.
  • Direct sow undercover in containers, moving them outdoors in June.

Even if a warm environment is provided in the early stages of growth, the plants could still bolt, especially if there is a cold snap. Tatsoi and mustard are particularly prone to bolting prematurely, and it is probably better not to grow them this early.

For main crops: As a base line, seed can be sown outdoors from June to August. You could try an earlier sowing of komatsuna and mizuna – they are quite bolt resistant and might produce good-size plants from a May sowing. Conversely, it might be worth delaying sowings of tatsoi and mustard until July since they are particularly susceptible to premature bolting.

You can establish a crop by direct seeding outdoors in containers or the ground. Alternatively, start plants as transplants, and keep them either outdoors or undercover until they are big enough to be planted outdoors.

Late August sowings may need to be put undercover as autumn progresses – otherwise growth will slow down due to the onslaught of cold weather. Even if growth does halter, the plants should still produce enough leaves to give a satisfactory yield.

For overwintering crops: Plants can be overwintered in a tunnel or greenhouse Get them started by direct sowing seeds undercover in the first half of September and then leaving the plants where they are. Alternatively, start the crop as transplants in the first half of September, planting them about mid-October when they are big enough to handle.

Growing on

Watering: Throughout the life of the crop, make sure that the plants are watered well enough to prevent a check in growth. Pay particular attention to those grown in containers – the compost tends to dry out quickly, especially on hot, windy days in the summer. If the containers are not too big, they can be placed in shallow trays filled with water – this maintains a reservoir of moisture that will last for days.

Fertilising outdoor crops: For oriental leaves grown in the ground, work a complete solid fertiliser into the soil before sowing or transplanting. Done right, there will be no need for extra feeding throughout the lifetime of the plants. This is not true, unfortunately, for a compost-grown crop in containers, which will need to be fertilised with a liquid feed two to three weeks after sowing or transplanting. A single feed may provide enough nutrients to see the crop through, but keep an eye on the slower bolting varieties – they go on producing for a longer time and may need an extra dose.

Fertilising undercover crops: Overwintered crops grown in the ground won’t need to be fertilised if they follow tomatoes, peppers, aubergines and cucumbers. These vegetables are normally given heavy applications of fertiliser, and there will probably be enough residual nutrients in the soil to keep oriental leaves growing throughout the winter.

Container crops grown undercover during the winter need to be fertilised, but less frequently than those grown outdoors in the summer and autumn. Therefore, use a light hand, and avoid the temptation to over fertilise – not only is it a waste of nutrients, but you could also cause an accumulation of nitrates in the plants.

Harvesting

To harvest, cut the plants at ground level, just below the lower leaves. There is no optimum harvest time per se – the plants continue to grow in size until they bolt, so the later they are harvested the bigger the plants will be.

 

2. Cut-and-grow-again for teenage leaves

Not only can oriental leaves be grown for single harvests when the plants are large-sized, they can also be harvested under a ‘cut-and-grow-again’ regime in which smaller plants are cut two or more times from a single sowing. In this system, plants are usually grown closer together, and harvests can be made quite quickly after sowing.

A cut-and-grow-again system is very flexible, and depending on the plant spacing, the leaves can harvested in a range of sizes. At one extreme are the baby leaves (see below) which are, as the name implies, quite small.

Further up the scale are the teenage leaves, harvested when they are bigger than baby leaves. Drawing a distinction between the two is somewhat arbitrary, and, like gardening, it is not an exact science.

Here at Sea Spring Seeds, we really like our teenage leaves: they come on quickly and are less fiddly to manage than baby leaves. Furthermore, they are almost a guaranteed success: though early sowings may bolt prematurely due to cold weather, they will produce at least one harvest before this happens. The growing technique is essentially the same as it is for large-sized plants – the only differences are the distances between plants and the harvesting method.

Growing distances

Grow plants 15 to 30cm apart, spacing them equidistant from each other, preferably in a triangular pattern. Go for a wider spacing if you plan on harvesting bigger leaves; grow closer together for harvesting smaller ones.

Harvesting

Teenage leaves can be harvested from plants that range in size from small (at least 15cm tall) to large (virtually full-sized). The larger outside leaves can be individually cut off the plants, leaving the inside ones to continue growing for later harvests. Alternatively, the whole plant can be harvested at one go by making a straight cut about 5 to 6cm above ground level, leaving the stump to regrow.

 

3.Cut-and-grow-again for baby leaves

This is a variation of the cut-and-grow-again system in which plants are grown at high densities and then harvested as ‘baby’ leaves. Growing for baby leaves is quite straight forward since transplants are never used. Instead, the seed are sown where the plants are to grow and develop. Large, compost-filled containers such as growbags and troughs are ideal for this system, though seed can also be sown in the ground if the soil is relatively weed-free.

To get started, sow seeds about 1cm apart in rows 10 to 12cm from each other. After they have emerged, thin out the seedlings, leaving 2 to 3cm between them. There are four main sowing times, each of which is treated differently to produce the best results:

For very early crops: Sow in March and April undercover, leaving the crop there for its duration. The plants may bolt prematurely from such an early sowing, but decent harvests are still possible before this happens.

Depending on the facilities available to you, crops grown at this time of the year can be managed in different ways:

  • Grow in the ground of a tunnel or greenhouse.
  • Grow in containers kept inside a tunnel or greenhouse.
  • Grow in the ground outdoors when the soil is dry enough to work; then cover the area with a cloche or cold frame.

For early crops: Sow in May undercover, then put outdoors when the weather turns warm – from the beginning of June is about right. As with the very early crops, the plants may bolt prematurely if there is a cold spell, but decent harvests are still possible.

If you sow at this time of the year, there are two effective methods for handling the crop:

  • Sow seeds in containers kept inside a tunnel or greenhouse; then move the containers outdoors in June.
  • Sow seeds in the ground outdoors, and cover the area with a protective structure such as a cloche or cold frame. Remove the protection in June.

For main crops: Sow outdoors in containers or the ground from June to August, and keep outdoors. Later sowings may need to go undercover if the weather turns cold in the autumn.

For overwintering crops: Sow undercover in containers or the ground in the first half of September. A tunnel or greenhouse is ideal.

Watering

Throughout the life of the crop, make sure that the plants are watered well enough to prevent a check in growth. Pay particular attention to those grown in containers – the compost tends to dry out quickly, especially on hot, windy days in the summer. If the containers are not too big, they can be placed in shallow trays filled with water – this maintains a reservoir of moisture that will last for days.

Fertilising outdoor crops

For crops grown in the ground, work a complete solid fertiliser into the soil before sowing. Done right, there will be no need for extra feeding throughout the lifetime of the plants. This is not true, unfortunately, for a compost-grown crop, which will need to be fertilised with a liquid feed two to three weeks after sowing or transplanting. A single feed may provide enough nutrients to see the crop through, but keep an eye on the slower bolting varieties – they go on producing for a longer time and may need extra feeding.

Fertilising undercover crops

Overwintered crops grown in the ground won’t need to be fertilised if they follow tomatoes, peppers, aubergines and cucumbers. These vegetables are normally given heavy applications of fertiliser, and there is probably enough residual fertility in the soil to keep oriental leaves growing.

Container crops grown undercover during the winter can be fertilised less frequently than those grown outdoors in the summer and autumn. Therefore, use a light hand, and avoid the temptation to over fertilise – not only is it a waste of nutrients, but you could also contribute to an accumulation of nitrates in the plants.

Harvesting

Cut the plants when they are 10 to 15cm tall. Make sure the cut is 1 to 2cm high (see Easy Peasy) to allow the stump to regrow. Generally, the plants will yield at least one more harvest before they start to bolt.

 

Easy Peasy Gardening for baby leaves

Easy Peasy Gardening is an alternative cut-and-grow-again system used to produce baby leaves, although in this instance the seeds are broadcast in compost-filled trays, troughs and pots. Because it is so simple to set up and run, this system is ideal for children and time-stressed adults. All that needs to be done is the following:

For very early crops: sow in March and April undercover, leaving the crop there for its duration. The plants may bolt prematurely from such an early sowing, but decent harvests are still possible before this happens.

For early crops: Sow in May undercover, then put the containers outdoors when the weather turns warm – from the beginning of June is about right. As with the very early crops, plants may bolt prematurely, but decent harvests are still possible.

For main crops: Sow outdoors from June to August, and keep outdoors. Later sowings may need to go undercover if the weather turns cold in the autumn.

For overwintering crops: Sow undercover in the first half of September and keep there for the duration of the crop.

Broadcast the seed quite densely in trays, troughs or pots filled with compost. After they emerge, thin out the seedlings to leave about 2 to 4cm between each one.

Harvest the plants when they are about 10 to 15cm tall, leaving a 1 to 2cm stump to regrow.

Keep the compost from drying out by watering the containers from above with a hosepipe or watering can. For extra protection, the containers can be placed in shallow trays filled with water – this maintains a reservoir of moisture that will last for days.

Outdoor crops will need to be fertilised with a liquid feed two to three weeks after sowing. This may provide enough nutrients to see the crop through, but keep an eye on the slower bolting varieties – they go on producing for a longer time and may need an extra application.

Crops grown undercover during the winter can be fertilised less frequently than those grown outdoors in the summer and autumn. Therefore, use a light hand, and avoid the temptation to over fertilise – not only is it a waste of nutrients, but you could also contribute to an accumulation of nitrates in the plants.

 

Problems

Bolting

Physiological stage when leaf production stops. Plants will eventually bolt though you can delay the inevitable by protecting young plants from the cold; keeping the crop well-watered; and growing bolt-resistant varieties such as Joi Choi and Broadleaved Mizuna.

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:

 

snail damage

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 the eggs off the plants, 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. Rotaions are essential. 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

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 the eggs off the plants, 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. Rotaions are essential. 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

 

© Michael Michaud