Chinese/Napa Cabbage and Oriental Leaves

These are brassica seeds that germinate fast. You are sowing them almost exclusively in the summer, so propagation is incredibly rapid. Sometimes seedlings can be ready to transplant within two weeks.

• Seeds germinate in three days with fully developed cotyledons in five days.

Sowing conditions

Seedlings are susceptible to flea beetle and caterpillar pests, and often slugs as well, so I recommend sowing only under cover. You don’t need too much space because of their speed of growth.

Sowing time

It’s best to wait until after the flowering season has finished before sowing. Therefore after midsummer, and preferably late summer is a good time to sow.

Best results at Homeacres for Oriental leaves are from sowings in early August; for under cover salads, we sow in mid-September.

Chinese cabbage for heads need sufficient time to grow into a head of good size, but also its best not to sow too early, otherwise insects do extra damage. There are two further reasons for not sowing too early:

• It will allow more time for preceding vegetables to finish cropping.
• Your harvest of heads will be ready closer to winter, at a time when they are probably more valuable because summer vegetables have finished.

Sowing method

For heads of Chinese cabbage and large stems of pak choi, you want one plant per module to make heads of a good size. It works well to scatter seeds in a small tray and then prick out before they are five days old. Or sow two seeds per module and thin to one.

Most Oriental leaves grow nicely in clumps of two or three. Sow three or four seeds per module, then thin to the number of plants you want in each module.

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The rapid growth of these seedlings means they are better transplanted as soon as possible. In late summer the soil is warm, and there is no need to pot on.

Transplant size

Small and young is good. The photos above show how Chinese cabbage is ready for transplanting after only two weeks.

The first time I transplanted such small seedlings, I wondered how it might work. Every late summer the results are always so strong that it’s become my standard practice.

When transplanting in cooler conditions, from mid-autumn, seedlings settle in better when three to four weeks old at transplanting – see these photos from October.

Transplant method

Using a long-handled dibber is quick for making holes, partly because these small seedlings are growing in small modules, so the holes are really quite tiny.

You are transplanting mostly in dry summer weather, so make holes a little on the deep side and water carefully after planting. Modules set deeper will hold moisture for longer.

Interplant

Chinese cabbage grows large so quickly that interplanting between anything else is not viable. Also, when it comes to the end of its life, time has run out for other interplants to go in between.

Oriental leaves on the other hand, and salad rocket, work well as interplants between other vegetables that are soon to finish, such as summer salads, ridge cucumber (cut off mildewed leaves first to make space), carrots and cordon tomatoes.

Spacing

For heads of Chinese cabbage: 30 –33 cm/12–13 in.

For Oriental vegetables to harvest leaves: 22 cm/9 in works for leaves over several months, or one cut of a head of pak choi.

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These are fast-growing plants and need plenty of moisture. Unless there is steady summer rain, you need to water regularly. In hot dry weather, I would aim for every second day, and a decent amount.

On a positive note, these brassica plants thrive in moist weather and suffer few leaf diseases, so when it rains you can relax in the knowledge that they are growing well. If the rain total is only small, on days of drizzle for example, it’s worth continuing with watering, especially for containers.

Extra mulch to retain moisture?

I suggest using only compost as mulch around Chinese cabbage and pak choi, because of the very high risk of slug damage resulting from undecomposed mulches. Slugs like these two vegetables more than any other.

Oriental leaves are at a close spacing, such that they provide leaf cover as mulch.

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How to judge readiness

For cabbage heads, it depends how firm you like them to be. Cut one in mid-autumn to see what it’s like inside.

• There is a reasonably long period of time in which to cut heads, from 70 to over 100 days from sowing.
• Heads of pak choi are ready within 40 days from sowing, and for perhaps a month after that. The longer you leave them, the more insects and other damage there will be on outer leaves.
• Oriental leaves and rocket are ready any time you want to eat them, as long as leaves are large enough to pick off. We allow plants to grow for 15–20 days after transplanting, before a first pick.

How to pick

You need a sharp knife to cut heads of Chinese cabbage and pak choi because of the strong fibres in the stems.

You can also use a knife to cut off outer leaves of pak choi and other Oriental leaf plants. Or, if your thumbnail is long enough, you can use it as a quick way to cut through stalks of larger leaves, such as mustards and rocket.

How often to pick

Even in autumn, growth can be fast, so you may be picking leaves every few days.

For heads of cabbage, it depends how many you planted – they come ready at a range of times from the same sowing, so watch your plants for readiness.

Insect damage to heads is a warning sign that they are better picked today or soon, especially if you see holes made by caterpillars going right inside – see below.

Storing

Heads of Chinese cabbage store well, as long as there is no insect damage. Aim for the harvest to be in late autumn, when the weather is cooler.

Best temperature for storing is below 10 °C/50 °F, simply in a box in a damp shed for example. I find that heads keep in good condition for a month or more. There are always a few wilting outer leaves to peel off before use.

Pak choi and Oriental leaves store less well, because they are mostly water and lose moisture rapidly from a high surface area. Even in a polythene bag, they also tend to go yellow after five days unless really cool – just above freezing point.

Saving seed

Seeding brassicas take up a lot of space in their second spring, as long as they survived winter. Best save seeds of only one variety at a time, which reduces your options.

I don’t want to discourage you but, for the cost of a few seeds, which store well, saving these seeds is perhaps not worth it.

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Which pests are likely, and when

• Slugs are the big pest for Chinese cabbage and pak choi. Every year I find that most vegetables are slug-free, or at least damaged only on older leaves which doesn’t matter. And yet, at the same time, often adjacent to these vegetables and growing in the same conditions with the same amount of moisture, there are many holes in younger leaves of Chinese cabbage and pak choi. I am unsure exactly why this is, I can only think that it relates to climatic differences between here and the regions of China and Asia where these vegetables originated, such that they are not quite at home in Somerset and weaker, therefore attractive to molluscs and pests generally. Or perhaps it’s their sheer speed of growth, making leaves soft and easy for pests to eat.
• Flea beetles damage seedlings, but not too much.
• Rabbits eat brassica seedlings, perhaps leaving only a stem.
• Caterpillars can decimate plants of Chinese cabbage, and do horrible damage to otherwise lovely heads. The main damage to Oriental leaves is by green caterpillars of cabbage moths.
• All the photos in the gallery below were taken on the same day in late October 2012, after a wet summer.

Protections needed

Mesh is the most effective preventive. Best use hoops to support it, and put in place straight after the transplant. Keep over plants for most of their lives, at least until mid-autumn when you see no more butterflies. The difficulty is with moths, which one rarely sees – the result of a moth caterpillar is shown in the middle photo above.

Bacillus thuringiensis is good against caterpillars only. Spray seedlings before transplanting, then ideally about five times every 16 days until mid-autumn.

Other likely difficulties

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There are a few plants that succumb to the rotting of outer leaves, and occasionally the main stem too – plants may then shrivel. I do not advise any remedy, because this happens most autumns and only after there have already been a lot of harvests. It’s an isolated occurrence rather than a general die-off.

• All the covers in the world are not a guarantee of success. These are difficult vegetables from that point of view, a challenge, but are so worth attempting for their speed of growth at a great time of year.

If your soil has clubroot, best read this:

Clubroot is relatively rare. Spores are most active in warm soil, therefore there is less damage to winter brassicas, but Chinese cabbage and Oriental leaves grow in warm autumn soil.

The result of clubroot infection is galls or swellings on roots and lower stems. These impede the uptake of nutrients and water.

It is spread in many ways: by the import of infected plants, from infected neighbouring plants, by use of infected tools, by moving infected soil and even from surface water runoff. Spores remain dormant for several years, until coming to life again on host plants.

• I am not aware of resistant varieties of Pekinensis and Chinensis.
• Clubroot thrives in slightly acid and wet soils. As with allium white rot, no dig reduces incidence. Perhaps also give a dusting of lime in spring every year, to lessen the damage.