How to grow Gai Lan in New Zealand
Gai lan, also called Chinese broccoli or kailaan, is a fast, leafy brassica grown for its thick, sweet stems, leaves and small flower buds, all eaten together. It is quicker and easier than ordinary broccoli, ready in about eight weeks, and cutting the main stem brings on a run of tender side shoots. Like other brassicas it needs protection from white butterfly caterpillars.
📖 Our full guide: How to Grow Gai Lan in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | February to April, August to October | |
| Auckland | February to April, August to October | |
| Waikato & Bay of Plenty | February to April, August to October | |
| Central North Island | February to April, September and October | Skip August in the central North Island. Plant from September and cover young plants on frosty nights. |
| Wellington & Lower North Island | February to April, August to October | |
| Nelson & Marlborough | February to April, August to October | |
| Canterbury | February and March, September to November | Start spring sowings in Sep under a cloche or frost cloth, as frosts run to mid October. Keep sowing through Nov with steady watering. Make the last sowing in Mar so the crop is ready before winter growth stops. |
| Otago & Southland | February and March, October to December | Start spring sowings in Oct under a cloche or frost cloth, as frosts run to late October. Cool summers let you keep sowing through Nov to Dec. Make the last sowing in Mar so the crop is ready before winter growth stops. |
| Central Otago | February, October and November | Start spring sowings in Oct under a cloche or frost cloth, as frosts run into early November. Keep sowing through Nov with steady watering. Make the last sowing in Feb so the crop is ready before winter growth stops. |
Where to plant
Grow gai lan in full sun in firm, fertile soil dug through with compost. It is a cool-season crop: it grows best in the mild weather of autumn and spring and tends to bolt to flower quickly in summer heat.
As a brassica, it belongs in the cabbage family part of your crop rotation. Avoid beds where brassicas grew recently, especially if clubroot has been a problem.
- Northland, Auckland, Waikato and Bay of Plenty, Wellington, and Nelson and Marlborough: sow from February to April and again from August to October. Ease off through the hottest weeks, when it bolts.
- Central North Island: sow February to April, then from September. Skip August, and cover young plants on frosty nights.
- Canterbury: sow in February and March, then from September to November. Start spring sowings under a cloche or frost cloth, as frosts run to mid October.
- Otago and Southland: sow in February and March, then from October to December. Cool summers let you keep sowing into early summer.
- Central Otago: sow in February, then in October and November under a cloche, as frosts run into early November.
Choosing a variety
| Variety | Notes |
|---|---|
| Gai lan or kailaan (white flower) | The standard open-pollinated type with thick stems, leaves and small flower heads |
| Green Lance F1 | A uniform hybrid with tender stems that crops quickly |
How to plant
- Prepare a sunny bed with compost and a general fertiliser, and firm the soil.
- Sow seed about 0.5 cm deep, in punnets to transplant or direct in the bed. Seed germinates best in soil of 15 to 25°C.
- Plant out or thin seedlings to about 25 cm apart, and water them in.
- Cover the bed with insect mesh or fine netting straight after planting to keep white butterfly off.
- Sow a small batch every few weeks through the sowing season for a steady supply.
Watering and feeding
Water regularly so growth stays fast and tender. Plants that dry out turn tough and run to flower early.
Feed every week or so with a liquid fertiliser for leafy vegetables, or side-dress with a nitrogen-rich fertiliser, to keep the stems thick and juicy.
Pruning and care through the year
- Keep insect mesh on until harvest. Check under leaves for caterpillars and eggs if you do not use mesh.
- Keep the bed weeded and mulched to hold moisture.
- Pick before the flowers open; once the plant is in full flower the stems turn stringy.
Harvesting
Harvest the main stem when the flower buds are visible but still tight, usually about eight weeks after sowing. Cut it about 10 to 15 cm long, taking stem, leaves and buds together.
Cutting the central stem triggers side shoots. Keep picking these over the following weeks, again before the buds open, to extend the crop.
Growing in pots
Gai lan grows well in a pot at least 25 cm wide filled with quality potting mix. Water often, feed every week or two with a liquid fertiliser, and cover it with insect mesh.
Companion planting
Gai lan is a quick crop that fits between slower vegetables. Like all brassicas it should move to a new bed each year as part of a rotation.
Good companions
- Beetroot A root crop that uses a different part of the soil and can share the bed.
- Onion Onions take little space and grow alongside brassicas in the same cool seasons.
- Dill Its flowers bring in hoverflies and parasitic wasps, which help control aphids and caterpillars.
Keep apart
Avoid planting these close to gai lan.
- Tomato Tomatoes are a summer crop that wants a different season and different feeding.
- Strawberry Traditional companion lists keep strawberries apart from cabbage family crops.
Pests and diseases
Gai lan shares the pests of other brassicas. Caterpillars are the main problem from spring to autumn, and covering the crop with insect mesh prevents most damage.
Pests to watch for
- White butterfly White butterflies around the bed, and green caterpillars and ragged holes in the leaves.
- Diamondback moth Small green caterpillars that wriggle when touched, and leaves with clear windows chewed in them.
- Aphids Grey, waxy clusters under leaves and on the buds, worst in dry weather.
Diseases to watch for
Common questions
When should I pick gai lan?
Cut the main stem when the flower buds have formed but are still tight, about eight weeks after sowing. Once the yellow or white flowers open, the stems get tougher. Keep picking the side shoots that follow.
Which parts of gai lan do you eat?
All of the top: the thick stems, the leaves and the small flower buds. They are usually cooked together, steamed or stir-fried, but young stems can be eaten raw.
Why is my gai lan flowering so early?
Heat, dry soil and stress make gai lan bolt. Sow it for the cooler months, keep it watered, and pick promptly. In the north, ease off sowing through the hottest part of summer.
How do I keep caterpillars off gai lan?
Cover the plants with insect mesh or fine netting from planting until harvest, and seal the edges. Without a cover, check under the leaves regularly and remove caterpillars and eggs.
Is gai lan the same as broccoli?
They are the same species, Brassica oleracea, but gai lan is grown for leafy stems and small buds rather than a big head. It is faster and easier than broccoli.
Can I grow gai lan in a pot?
Yes. Use a pot at least 25 cm wide with good potting mix, keep it watered and fed, and cover it with insect mesh.
Sources we checked: Kings Seeds NZ: Broccoli Chinese Gai Lan; Yates NZ: How to grow Asian greens.