Chinese Cabbage

Start from seed: November-early March

Optimum soil temperature for germination: 10-20°C

Plant seedlings: November-March

Plant spacing: 30-40 cm

Days to maturity: 55-70 days

Introduction

Chinese cabbage (Brassica rapa var. pekinensis), also known as Wombok, Wong Bok or Napa cabbage is a member of the Brassicaceae family, which includes other vegetables like broccoli, cauliflower, cabbage, kohl rabi, collards, radish, turnips, rocket, mustard and kale.

Chinese cabbage is not a naturally occurring species but is thought to be a cross between a warm climate leafy Brassica species, such as Bok choy, and a cool climate turnip. Archaeological evidence suggests it originated in China over 6,000 years ago, and it remains a staple vegetable throughout East Asia.

The plant forms an elongated head with tightly wrapped, crinkled leaves that are pale green on the outside and white to pale yellow inside. There are also beautiful re varieties. It has a milder, sweeter flavour compared to regular cabbage and a tender, crisp texture that makes it versatile for both raw and cooked applications. It’s rich in vitamins A and C, as well as calcium and dietary fibre.

Site and soil

Chinese cabbage grows well in Canberra’s after the summer solstice in late summer and early autumn when day length is decreasing. It can be grown in spring if care is taken to avoid bolting which can be triggered by water stress, heat and transplant shock. Wombok prefers full sun during cooler months but benefits from partial shade during warmer weather to prevent premature bolting (flowering).

Prior to planting, prepare the soil by incorporating compost and a balanced organic fertilizer. Cabbage prefers a fertile, well-drained soil with a pH between 6.0-6.5. It is commonly thought that they prefer alkaline soil. This is because clubroot disease can be problematic in acidic soils. If this is the case liming to raise the pH above 7.0, ideally to 7.8, is beneficial.

For container growing, use a large pot at least 30 cm deep filled with premium potting mix enhanced with compost and slow-release organic fertilizer.

For details on preparing soil and pots, including the use of lime, dolomite, gypsum and fertilizers, please refer to the COGS guide to garden bed preparation.

Planting Seeds and Seedlings

Chinese cabbage can be direct-sown or grown as seedlings. Direct sowing is advised in spring to avoid transplant shock that may trigger bolting. Sow seeds from late November to early March.

When direct-sowing, plant seeds twice the depth of the seed in rows 30-40 cm apart. Thin seedlings to 30-40 cm apart when they have 2-3 true leaves. Chinese cabbage germinates quickly, typically within 3-5 days if kept moist.

For seedling production, sow in cell trays or flat trays filled with seed-raising mix. Seedlings are ready for transplanting when they have 4-5 true leaves, usually 3-4 weeks after sowing.

After planting, water thoroughly with a seaweed solution to reduce transplant shock and apply organic mulch to retain moisture and suppress weeds.

Cultivation

In Canberra, plant Chinese cabbage after the summer solstice in late summer and early autumn when day length is decreasing. Avoid planting in mid-summer when high temperatures can cause premature bolting or in mid-winter when growth will be slow.

Chinese cabbage needs consistent moisture for proper head formation and to prevent bitterness. Water regularly, keeping the soil evenly moist but not waterlogged. Water and heat stress can lead to tough, bitter leaves and premature flowering.

Apply a balanced organic fertilizer when planting and side-dress with additional fertilizer when plants are about half-grown. Regular applications of seaweed solution; a mix of worm juice, seaweed and compost tea; or trace elements can boost growth and improve resistance to pests and diseases.

Keep the growing area weed-free, especially when plants are young, as Chinese cabbage doesn’t compete well with weeds. Maintain mulch to suppress weeds and conserve moisture.

For the best quality heads, Chinese cabbage should grow quickly with steady, uninterrupted growth. Temperature fluctuations or other stresses can trigger premature bolting, especially in spring crops.

Harvesting

Chinese cabbage is ready to harvest when heads are firm and have reached their expected size, usually 8-10 weeks after sowing. Heads should be compact and feel solid when gently squeezed.

Harvest by cutting the entire head at the base with a sharp knife. You can also harvest individual outer leaves if you prefer, allowing the plant to continue growing.

For spring-planted Chinese cabbage, harvest before hot summer weather causes bolting. For autumn-planted crops, harvest before severe frost, although Chinese cabbage can tolerate light frost, which can actually improve flavour.

Chinese cabbage stores well in the refrigerator for up to 6 weeks. Wrap heads in plastic or store in the crisper drawer to maintain freshness.

Problems

There are numerous pests and diseases that can affect Chinese cabbage. The best approach is to have a reliable Australian reference book to identify problems. Garden Pests, Disease and Good Bugs by Denis Crawford is recommended.

A general strategy to follow with any problem is to observe the plant carefully before taking action. Identify the problem then carefully consider the course of action. For example, with pest insects, you often can see a predator nearby. If you watch and wait the predator may deal with the problem for you. Beneficial predatory insects which feed on pest insects can be purchased from suppliers such as Bugs for Bugs. If the problem needs further action the above recommended book has suggestions.

Practicing good garden hygiene, crop rotation, and maintaining plant vigour by providing adequate nutrients are key strategies for prevention.

Chinese cabbage can face several challenges in Canberra gardens:

Cabbage White Butterfly (Pieris rapae): This common pest lays tiny white eggs on the undersides of leaves. The green caterpillars that hatch are perfectly camouflaged and feed on leaves, creating irregular holes and contaminating plants with their droppings. Exclusion netting is the most reliable method to prevent damage from cabbage white butterfly. Keep in mind that the netting also excludes beneficial insects and birds that glean plants cleaning up other pests. Thus, leaving the netting on for too long can result in populations of sap suckers such as aphids, thrips and white fly building up inside the netting.

Control methods include:

Covering plants with fine insect mesh or exclusion netting from the time of planting
Regularly inspecting and manually removing eggs and caterpillars
Using biological controls such as Bacillus thuringiensis (also known as Bt and sold as Dipel) for significant infestations
Creating butterfly decoys by placing white plastic pieces around plants
Avoiding brassica weeds that act as hosts

Clubroot (Plasmodiophora brassicae): This soil-borne disease causes swollen, deformed roots and stunted growth. Plants may wilt during warm weather and show yellowing leaves. The disease thrives in acidic soils (below pH 7.0) and can persist in soil for many years. Management includes:

Maintaining soil pH above 7.0, ideally 7.8, through liming
Practicing crop rotation (avoid planting brassicas in the same area for at least 4 years)
Improving drainage in wet areas
Removing and disposing of infected plants (do not compost)
Using disease-free transplants and clean tools

Aphids, thrips and white fly: These small sap-sucking insects can transmit celery mosaic virus. They often cluster on the undersides of leaves, causing distortion and stunting. Small populations can be controlled by washing them off with a strong stream of water or using insecticidal soap. Alternatively, neem oil or pyrethrin can be used. Beneficial predators like ladybugs and lacewings should be encouraged and can be purchased for release on the crop. Look for aphid mummies which are evidence that the aphid has been parasitised. Eggs can also be parasitised and will appear bronze in colour. Generally speaking, plants that are high in soluble nitrogen (nitrates and ammonia) are prone to attack by sap sucking insects. Ideally avoid using soluble nitrogen fertilisers and ensure plants have adequate trace elements. This can be achieved by using foliar sprays.

Slugs and Snails: Slugs and snails like to hide in between the leaves damaging young seedlings, creating holes in leaves and wreaking havoc in larger plants. Control using beer traps, copper tape barriers, or organic (iron EDTA) snail baits.

Bolting: Premature flowering can occur due to stress from temperature fluctuations, water and heat stress, or transplant shock. Prevent by planting at appropriate times and ensuring consistent growing conditions.

Recommended Varieties

Several Chinese cabbage varieties perform well in Canberra’s climate:

Wong Bok (Napa) Types:

Blues – Early maturing variety with good bolt resistance
Yuki – Compact heads with excellent flavour and disease resistance
Jirisan or Merlot – red compact heads with excellent flavour and disease resistance
Michihili – Tall, cylindrical heads; tolerates cool weather well
Kasumi – High-quality hybrid with good disease resistance and uniform heads

Specialty Types:

Minuet – Mini Wong Bok type, perfect for small gardens
Rubicon – Excellent bolt resistance and uniform heads
Bilko – Dark green outer leaves with a yellow interior; good cold tolerance

For Canberra’s climate, focus on bolt resistant varieties for spring plantings and cold tolerance for late summer and early autumn plantings. Hybrid varieties generally offer better disease resistance and more uniform growth than open-pollinated types.

References

Bubel, Nancy. The New Seed-Starters Handbook. Rodale Books, 2018.
Crawford D. Garden Pests, Disease and Good Bugs. Australia: ABC Books; 2015.
Department of Primary Industries and Regional Development. (n.d.). Managing clubroot in vegetable brassica crops. https://www.agric.wa.gov.au/broccoli/managing-clubroot-vegetable-brassica-crops
Dove, Helena. Botany of the Kitchen Garden, Kew Publishing, Royal Botanic Gardens Kew, UK, 2023.
Fanton, Michel and Jude. The Seed Savers Handbook. The Seed Savers Network, Australia, 1993.
Johnny’s Selected Seeds. (2022). Growing Cabbage From Seed. https://www.johnnyseeds.com/growers-library/vegetables/cabbage/cabbage-key-growing-information.html
Yates Australia. (2024). How to Grow Cabbage. https://www.yates.com.au/how-to-grow/cabbage/