How to grow Komatsuna in Australia
Komatsuna, also called mustard spinach, is a fast Japanese leafy green (Brassica rapa) with glossy, dark green leaves and a mild flavour somewhere between spinach and mustard. It is ready to pick in about five weeks, handles frost well, and copes with a little more heat than most Asian greens.
📖 Our full guide: How to Grow Komatsuna in Australia
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| South East Queensland | February to September | |
| Northern Rivers NSW | February to September | |
| Sydney & Coastal NSW | February to September | |
| Melbourne & Victoria | March to September | Sow Mar to Sep. Komatsuna shrugs off Melbourne frost and is ready in five weeks. Summer sowings bolt. |
| Adelaide & SA | March to September | Sow Mar to Sep. Komatsuna is quicker and more heat tolerant than most Asian greens, but still bolts from late spring. |
| Perth & WA | March to September | Sow Mar to Sep. Komatsuna is quicker and more heat tolerant than most Asian greens, but still bolts from late spring. |
| Tasmania | August to March | Sow Aug to Mar. Komatsuna shrugs off Tasmanian frost. Fast and dependable. |
| Canberra & ACT | February to April, September and October | Sow Feb to Apr for autumn and winter, or Sep to Oct for spring. Komatsuna is among the hardiest greens once established. |
| North Queensland | May to September | Dry season May to Sep. Komatsuna takes more heat than most Asian greens but still bolts in the build up. |
| Darwin & Top End | May to September | Dry season May to Sep. Komatsuna takes more heat than most Asian greens but still bolts in the build up. |
Where to plant
Grow komatsuna in sun or part shade in fertile soil with plenty of compost that stays moist but drains well. It is quick and compact, so it fills gaps between slower crops and grows well in pots.
Komatsuna is a member of the cabbage family. Rotate it with other brassicas and do not grow it where clubroot has been a problem.
- South East Queensland, the Northern Rivers and Sydney: sow from late summer to early spring.
- Melbourne, Adelaide and Perth: sow from March to September. It bolts once late spring warms up.
- Canberra: sow from February to April for autumn and winter, or in September and October for spring. It is among the hardiest greens once established.
- Hobart: sow from August to March; it shrugs off frost.
- North Queensland and Darwin: sow in the dry season, May to September. It still bolts in the build up.
Choosing a variety
- Green komatsuna has dark green, glossy leaves with a mild flavour.
- Red komatsuna has purple-red leaves with the same flavour and adds colour to salads.
How to plant
- Sow seed direct, about 0.5 cm deep, in rows or scattered thinly, and cover lightly.
- Keep the soil moist. Seedlings appear within about a week.
- Thin to 15 to 20 cm apart for full-size plants, or leave them closer for baby leaves.
- Sow a small batch every few weeks for a steady supply.
Watering and feeding
Keep the soil evenly moist for fast, tender growth. Dry soil and heat make the leaves tough and push the plant to flower.
Feed with compost at sowing and a nitrogen-rich liquid fertiliser every couple of weeks while you are picking.
Pruning and care through the year
- Cover with insect mesh, pegged down at the edges, when cabbage white butterflies or flea beetles are about.
- Pick often and remove flower stems to keep plants leafy for longer.
Harvesting
Pick outer leaves once plants are a good handful in size, from about five weeks, and the centre keeps producing. Or cut the whole plant young.
Leaves keep for three to four days in a sealed bag in the fridge.
Growing in pots
Komatsuna grows well in a pot or trough at least 20 cm wide with good potting mix. Water often, as pots dry out quickly.
Using it
Use young leaves raw in salads. Larger leaves and stems are good stir fried, in soups and noodle dishes, or lightly steamed, much as you would use spinach or bok choy.
Companion planting
Komatsuna is fast and compact, so it is handy for gaps between slower crops. Keep it out of beds where other cabbage family crops grew recently.
Good companions
- Lettuce Another quick, shallow-rooted leafy crop that likes the same moist soil.
- Beans A different plant family, so it fits a rotation after or beside beans without sharing their pests.
Keep apart
Avoid planting these close to komatsuna.
- Brassicas Do not follow other cabbage family crops in the same bed, which builds up clubroot and shared pests.
Pests and diseases
Komatsuna grows so fast that it rarely struggles, but it shares the cabbage family's pests.
Pests to watch for
- Flea beetle Tiny jumping beetles making small round holes in young leaves in warm, dry weather.
- Cabbage moth Green caterpillars and ragged holes in the leaves. Cover with mesh or pick off caterpillars.
Diseases to watch for
- Clubroot Plants wilt on warm days and stay stunted; roots are swollen and distorted. It persists in soil for years, so rotate brassicas and lime acid soil.
Common questions
What is komatsuna?
A Japanese leafy green in the cabbage family, Brassica rapa, also called mustard spinach. It has glossy dark green leaves with a mild flavour between spinach and mustard.
How fast does komatsuna grow?
Very fast. Leaves can be picked from about five weeks after sowing, earlier as baby leaves.
Can you eat komatsuna raw?
Yes. Young leaves are mild enough for salads. Larger leaves and stems are good stir fried, in soups or lightly steamed.
Is komatsuna frost hardy?
Yes. It handles frost well, which makes it a good winter green in Melbourne, Canberra and Hobart.
Why is my komatsuna bolting?
Warm weather and dry soil make it flower. Sow in the cooler months, keep the soil moist, and pick often.
Sources we checked: Local Food Connect (Robin Gale-Baker): Mustard greens and mizuna (Brassica rapa types including komatsuna); RHS: How to grow mizuna and mibuna (oriental greens, grown the same way); RHS: Clubroot.