How to grow Mustard Greens in New Zealand
Mustard greens are fast, leafy brassicas with a peppery, mustard bite, used young in salads and older in stir-fries, curries and braises. Red Giant, with big purple-red leaves, is as decorative as it is tasty, and gai choy is the classic Chinese mustard green. They are cool-season crops: ready in about a month, and quick to bolt in summer heat.
📖 Our full guide: How to Grow Mustard Greens 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, August to October | |
| Wellington & Lower North Island | February to April, August to October | |
| Nelson & Marlborough | February to April, August to October | |
| Canterbury | February to April, 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. |
| Otago & Southland | October to March | 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 Jan. Make the last sowing in Mar so the crop is ready before winter growth stops. |
| Central Otago | February and March, 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 Mar so the crop is ready before winter growth stops. |
Where to plant
Grow mustard greens in sun or part shade in fertile, well-drained soil enriched with compost or blood and bone. They grow best in the cool weather of autumn, winter and spring. Heat and dry soil make the leaves harsher and send plants to seed.
They are brassicas, so rotate them with the cabbage family and cover them against white butterfly in the warmer months.
- Northland, Auckland, Waikato and Bay of Plenty, the central North Island, Wellington, and Nelson and Marlborough: sow from February to April and from August to October.
- Canterbury: sow from February to April and from September to November, using a cloche for September sowings.
- Otago and Southland: sow from October to January and in February and March, with a cloche for October sowings.
- Central Otago: sow in October and November under a cloche at first, and in February and March.
Choosing a variety
| Variety | Notes |
|---|---|
| Red Giant | Large, savoyed, purple-red leaves with green undersides; winter hardy and slow to bolt, and the red deepens in cool weather |
| Gai choy | A common Chinese mustard green with crisp, thick leaves; eaten raw, boiled, steamed or stir-fried |
| Green mustard (for example Southern Giant) | Broad, ruffled green leaves with a hot tang |
How to plant
- Sow seed direct about 6 mm deep, in clumps of two or three or in rows. Seed germinates in about 5 to 10 days.
- Thin to 15 cm apart for baby leaves or 25 to 30 cm for larger plants. Use the thinnings in salads.
- Keep the soil moist, and cover with insect mesh in warm weather.
- Sow small batches every few weeks for a continuous supply.
Watering and feeding
Keep the soil evenly moist for tender, milder leaves. Dry plants turn hot, tough and bolt.
Feed weekly with a liquid fertiliser for leafy vegetables once seedlings are up.
Harvesting
Cut baby leaves from about four weeks, when plants are 10 to 15 cm tall, just above the soil, or pick the outer leaves of larger plants at about six to seven weeks and let the centre keep growing. Growth is slower in the cooler months.
Young leaves are mildest and good raw. Older leaves are hotter and best cooked. Mustard greens keep about four days in the fridge in a damp cloth.
Growing in pots
Mustard greens grow well in pots at least 25 to 30 cm wide in sun or part shade. Keep them moist and feed weekly. Red Giant is especially attractive in containers.
Companion planting
Mustard greens are quick, so they fit between slower crops in a cool-season bed.
Good companions
- Beetroot A root crop that shares the bed and the same cool seasons.
- Carrot Carrots grow slowly below while the mustard crops quickly above.
Keep apart
Avoid planting these close to mustard greens.
- Tomato A summer crop with different needs; traditional lists keep it apart from brassicas.
Pests and diseases
Mustard greens share the pests of other brassicas, but their quick growth means many crops are picked before pests build up.
Pests to watch for
- White butterfly Green caterpillars and ragged holes in the leaves, mainly spring to autumn.
- Slugs Seedlings and young leaves chewed overnight.
- Aphids Grey, waxy clusters under leaves.
Diseases to watch for
- Downy mildew Yellow patches on the upper leaf with fuzz underneath, in cool, damp weather.
Common questions
How fast do mustard greens grow?
Leaves are ready from about four weeks after sowing, a little longer in the cooler months.
Why are my mustard greens so hot?
Older leaves, heat and dry soil all make mustard greens hotter. Pick young leaves, keep the soil moist and grow them in the cool months.
When should I sow mustard greens?
In most of New Zealand from February to April and August to October. In Otago and Southland sow from October through summer, and in Central Otago in October and November and in February and March.
Can I eat mustard greens raw?
Yes. Young leaves are good in salads; older leaves are best cooked in stir-fries, curries and soups.
Why has my Red Giant gone green?
The red colour is strongest in cool weather and full sun. In warm weather or shade the leaves can be greener.
Sources we checked: Yates NZ: How to grow mustard; Kings Seeds NZ: Mustard Giant Red; Kings Seeds NZ: Mustard Gai Choy.