How to Grow Mizuna
Brassica rapa var. nipposinica
Mizuna is a fast, cool-season Japanese mustard suited to full sun or light shade and moist, fertile soil. Sow from spring and again late summer–autumn; plants tolerate light frost. Heat and drought trigger bolting, so keep moisture even and consider shade in midsummer. Harvest as baby leaves or let rosettes size up and cut whole. Protect seedlings from flea beetle with mesh. Regular picking keeps plants tender and productive.
When to Start
Direct sow outdoors as soon as soil reaches 6°C — typically early to mid spring. Can also be started indoors 3 weeks earlier for a head start.
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Growth Stages
Approximate days from start
Care Essentials
- Light liquid feed every 2 weeks. Needs consistent moisture.
- Fast-growing Asian green. Mild, peppery flavour. Sow from spring to autumn for year-round supply.
Growing Conditions
- Min. soil temperature
- 6°C+
- Germination temperature
- 10–20°C
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
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Spacing & Planting
| Plant spacing | 20 cm |
| Row spacing | 30 cm |
| Sow depth | 0.5 cm |
| Mature height | 30 cm |
| Mature spread | 25 cm |
A fast-growing Japanese green. Can be harvested as a 'cut-and-come-again' crop when sown more densely.
Pests & Diseases
Pest Flea Beetle
Identification: Tiny round shot-holes peppered across leaves, small shiny black beetles that jump when disturbed
- Cover with fine insect mesh from sowing
- Water regularly to encourage fast growth through vulnerable stage
- Sticky yellow traps placed near plants
- Pyrethrum-based spray as a last resort
Pest Slugs and Snails
Identification: Irregular holes in leaves, seedlings eaten overnight, slime trails on soil and foliage
- Beer traps near rows
- Nematode biological control (Nemaslug)
- Evening hand-picking
- Ferric phosphate pellets (wildlife-safe)
Pest Cabbage White Caterpillars
Identification: Ragged holes in leaves, green or yellow-black caterpillars, clusters of yellow eggs on leaf undersides
- Cover with insect mesh
- Hand-pick caterpillars and eggs
- Bacillus thuringiensis (Bt) spray
- Limited options for edible crops
Disease Downy Mildew Hyaloperonospora parasitica
Symptoms: Yellow patches on upper leaf surfaces, grey-white fuzzy growth underneath, leaves brown and collapse
Treatment: Remove affected leaves. Improve air circulation.
Prevention: Space plants well. Avoid overhead watering. Ensure good drainage. Rotate brassica crops.
Disease White Blister Albugo candida
Symptoms: Raised white blistery pustules on leaf undersides, corresponding yellow patches on upper surfaces
Treatment: Remove affected leaves. Plants usually recover if infection is mild.
Prevention: Space plants for airflow. Avoid overhead watering. Rotate brassica crops on a 3-year cycle.
Growing Conditions
| Min. soil temperature | 6°C |
| Germination temperature | 10–20°C |
| Base growth temperature | 4°C |
| Min. daylength to start | 9h |
| Photoperiod sensitivity | long day |
Frequently Asked Questions
- How far apart should I plant Mizuna?
- Plant Mizuna 20cm apart with 30cm between rows.
- When can I harvest Mizuna?
- Mizuna is ready to harvest approximately 30 days after transplanting.
- Is Mizuna frost hardy?
- Mizuna is classified as Hardy.
