Many Asian vegetables grow best under milder conditions – not too hot or too cold, so autumn is a great time to grow these versatile and nutritious vegetables. Most of us think of Bok Choy or Pak Choi as being the main Asian vegetables but there are others that are also great to use in your everyday cooking such as wombok and Chinese broccoli. These are just as easy to grow.
CHINESE CABBAGE (Brassica rapa)
This is one of the most widely grown asian greens
Brassica rapa is made up of several sub-species that include turnips and canola oil (Brassica rapa ssp. oliefera: ssp. pekinensis (Chinese cabbage e.g. wombok/sui choi, pe-tsai) and ssp. Chinensis (e.g. bok choy, pak choi and celery mustard). There are many cultivars within these two groups.
These Asian vegetables thrive in a fertile, medium textured, well-drained soil - they also:
- Prefer full sun.
- Are best grown in the cool season; ideal temperature for growth is 13 -18°C
- Can tolerate light frost.
- Need an ideal pH of around 7 (neutral) – add some dolomite lime to the beds or plant them to follow a previous carrot crop (which was already limed).
- Like the soil moist – all leafy vegetables need moisture to grow well and be sweet to taste.
- Need to be watered regularly to keep the plants growing strongly – water stress can induce bolting.
HINT: Never add lime and manures or fertiliser at the same time; the lime reacts with the nitrogen in the fertiliser or manures and turns it into a gas which then escapes into the air and is no longer available to your plants! Use dolomite instead – this is very slow acting and doesn’t react like garden lime does (making it a better option). Dolomite is a mix of calcium and magnesium and also reacts by reducing sodium in soils making it ideal for sodic clay soils too.
Wombok, Bok choy/Pak choi can be planted by direct seeding or transplanting, however transplanted seedlings can tend to ‘bolt’ (go to seed) so if possible direct sow, or sow seed into individual containers so that the roots are not disturbed when you transplant. Green stemmed varieties are hardier than the white stemmed types.
In cool areas such as those of the UK sow seeds 2cm deep in mid-spring through to mid- summer in rows allow 30 – 40cm between rows and similar between plants for larger varieties – smaller types can be planted at 15cm between plants. Sow seed along the row - the thinnings can be used as baby vegetables.
Earlier sowing will need to be protected with a cloche or similar.
In cool temperate areas sow seed in early spring and again in mid-autumn. The ideal growing temperature is 15 - 20°C; plants tend to run to seed (bolt) in hot conditions.
Chinese cabbages are not heavy feeders (in fact heavy nitrogen application can trigger soft rots) but they do require some nitrogen so prepare your soils well before hand adding lots of compost and manure as well as a handful per square metre of an organic pelletised fertiliser.
Use a liquid feed such as seaweed and fish emulsion fortnightly to keep the plants growing actively.
Pests and Diseases
- Aphids, cabbage white butterfly, flea beetle (in some areas) you can just try to wash aphids off with a hose or use pyrethrum (but remember that this can kill or disturb beneficial insects too). The best way to avoid cabbage white butterfly and flee beetle is by using exclusion fabric. Just make a tent over the top of the beds.
- Downy mildew (Peronospora parasitica), powdery mildew (Erisyphe polygoni) and Leaf spot (Alternaria brassicae) – these are fungal diseases: Avoid excessive nitrogen which encourages these problems; humid weather encourages these diseases too so make sure that there is plenty of air movement around your plants. Crop rotation is important to stop the spread of soil borne disease.
- Rot (Sclerotinia sclerotiorum) this is also a fungal disease and is most common in wet or waterlogged conditions – make sure that you plant in raise beds and that your soil is well-drained. Avoid heavy applications of nitrogen fertilisers.
Harvest and Use
- Harvest when the heads are fully developed; typically matures 45 -75 days after sowing depending on the variety.
- Sow successively (small rows) throughout the growing season (every 3 weeks or so) to extend the harvest.
- Cut wombok the heads off at ground level and remove the outer leaves. For Bok Choy/ Pak choi you can harvest the outer leaves as you need them and leave the plant to grow on or you can wait until mature and cut off at ground level.
- Chinese cabbage isn’t suitable for freezing so is best eaten fresh.
Chinese cabbage: ‘One Kilo Slow Bolt’.
Pak Choi 'Chokito', ‘Bok choy’, 'Red Choi'’, ‘Joi Choi’ (slow to bolt and frost resistant) ‘Canton Dwarf’.
USING ASIAN GREENS
Asian greens can be enjoyed in a variety of ways – we all know about stir frying! But these vegetables can also be gently poached in a chicken stock along with a teaspoon of soy, some grated ginger, grated garlic, drain well and just finish off with a few drops of sesame oil and toasted sesame seeds stir fry on A BBQ - most Asian greens are cooked quite quickly so you would need to watch that they don’t burn. Chinese broccoli is very useful on the BBQ because it retains its integrity very well; BBQ the broccoli along with some ginger and garlic and then serve.
Asian greens, oyster sauce, garlic and sesame seeds and sesame oil are a perfect combination. Whether you decide to steam, poach, stir fry or BBQ, topped with these ingredients you turn ordinary Chinese greens into a gourmet dish.
Wombok (finely sliced or shredded) also make a very nice coleslaw along with grated carrot, chopped spring onions, toasted sesame seeds and a sauce of combined olive oil (a couple of tablespoons) a teaspoon of soy sauce, a few drops of sesame oil, the juice of half a lemon and a scant teaspoon of honey. Pour over the finely sliced vegetables and serve sprinkled with extra toasted sesame seeds.
Also use them in soups and noodles – this versatile group of greens adds nutrition and flavour to almost any dish.
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