Chinese veggies with good prospects locally

The Pak choi vegetable. It is a cool season vegetable that belongs to the cabbage, spinach and cauliflower family and native to China. FILE PHOTO | NATION MEDIA GROUP

What you need to know:

  • Pak choi prefers rich, well-ploughed, well-drained, loamy soils with high fertility, organic matter and good water retention.
  • Ideally, Pak choi should be grown in full sun in cool regions and in partial shade in warm regions.
  • Pak choi is a shallow-rooted crop and requires frequent watering. Light irrigation should be applied as needed to keep the soil moist but not soggy. Overhead irrigation should, however, be avoided to prevent the potential spread of diseases.
  • Good soil aeration helps control bacterial soft rots, as the application of agricultural lime at least four weeks before sowing help in controlling incidence and severity of clubroot.

With the Chinese population rapidly rising in the country due to the ongoing infrastructure projects, it is time savvy farmers think of growing food for this niche market.

One of the crops to consider farming, which is much loved in the Asian nation, is a vegetable called Pak choi (Brassica rapa var chinensis), also known as bak choi or pak choy.

The crop is a cool season vegetable that belongs to the cabbage, spinach and cauliflower family, and is native to China, but has rapidly gained popularity among consumers around the world due to its mild flavour and suitability as a stir fry vegetable.

Climate and soils

Pak choi prefers rich, well-ploughed, well-drained, loamy soils with high fertility, organic matter and good water retention. The ideal soil pH is 6.5-7.0. Pak choi is sensitive to acidic conditions below pH 6.0, therefore, a soil pH of below 6.0 should be amended by applying agricultural lime at least four weeks before sowing.

Temperature and frost

Pak choi is a cool season crop that prefers moist and uniform conditions in full sunlight.

The ideal temperature during growth is 15-20°C as high temperatures with long days induce bolting. Most varieties can tolerate light frosts. Partial shade can help prevent the crop from bolting.

Ideally, Pak choi should be grown in full sun in cool regions and in partial shade in warm regions.

Propagation

Pak choi seeds are extremely small and, therefore, difficult to handle when sowing. Either sow directly into the row and thin to an appropriate spacing, or transplant 15-30 days after seeding, depending on the variety.

Pak choi does not transplant well, but transplanting may reduce bolting in relatively hot regions. The soil should be well-prepared so that the beds are raised with good drainage and air circulation.

The recommended spacing is 2.5–10cm (within row) for the smallest varieties and up to 45cm for the largest and 15–30cm (between rows) at a depth of 1–2cm below the soil surface.

Pak choi is a shallow-rooted crop and requires frequent watering. Light irrigation should be applied as needed to keep the soil moist but not soggy. Overhead irrigation should, however, be avoided to prevent the potential spread of diseases.

Pests and disease management

The most common problems affecting pak choi are clubroot, downy mildew, white rust, aphids, caterpillars and snails/slugs. Insect pests can be managed using pesticides.

Disease incidences can be minimised by planting tolerant varieties, avoiding handling the plants when wet, removing and destroying infected plants and application of recommended fungicides.

Weeds can be controlled by inter-row cultivation, but avoid working too deep as pak choi has a shallow root system.

Good soil aeration helps control bacterial soft rots, as the application of agricultural lime at least four weeks before sowing help in controlling incidence and severity of clubroot.

Harvest and utilisation

Harvest the crop when it reaches heights of about 1 to 2 feet tall. Depending on consumer preference and market demands, Pak choi can be harvested as whole heads or leafy vegetable.

It is ready for harvest in 30 days from sowing as baby leaf, or between 45-75 days as semi-mature to full-size heads. Pak choi is usually harvested by hand, that is, cut or pick fresh and crisp leaves from the base before the outer ones turn yellow. Alternatively, harvest whole heads at soil level when they are compact and firm and before seed stalks form.

Pak choi is extremely susceptible to wilting. Harvesting should, therefore, be done during a cooler part of the day. However, at 1°C and relative humidity greater than 85 per cent, pak choi can be stored for 7 – 20 days after harvesting.

Farmers can get seeds from major agrovets, especially those that stock Amiran seeds.

The veges grow in cool regions in high altitude areas in Mt Kenya, Njoro, Mau Narok, Timboroa, Limuru and Kiambu. Market for the produce include Chinese restaurants, individual customers and at the City Market in Nairobi, where a kilo goes for up to Sh150.

The writer is based at Department of Crops, Egerton University.