Mizuna
Brassica rapa var. nipposinica
Also known as: Japanese mustard greens, Kyona, Spider mustard
Quick facts
- Category
- leafy greens
- Difficulty
- beginner
- Days to harvest
- 25 to 40 days
- Harvest type
- cut leaves, plant regrows for repeated harvests
- Spacing
- 15 cm between plants
Environment
- Temperature
- 10–22°C
- pH
- 6 to 7
- EC (hydroponic)
- 1 to 1.8 mS/cm
- Daily light
- 10 to 15 mol/m²/day
Climate and zones
- USDA zones
- 4 to 9 (winter low around -34°C or warmer)
- Frost tolerance
- frost hardy (handles regular frost)
- Season
- cool (spring and fall crops)
Viable growing environments:
- outdoor year-round (in zone)
- outdoor in growing season (annual)
- unheated greenhouse / hoop house
- heated greenhouse
- indoor (heated home)
- indoor hydroponics under grow lights
USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.
Growing systems
Mizuna works in:
- deep water culture (rafts)
- NFT channels
- vertical / aeroponic tower
- media bed (ebb and flow)
- wicking bed
- soil bed
Growing media
The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (mizuna works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Net pot, no medium (Bare-root) | - | - | - |
| Soil-based mix (Potting soil) | varies by source | high | high |
Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.
Nutrient demand by stage
NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.
| Stage | N | P | K | EC target (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.6 |
| vegetative | 3 | 1 | 2 | 1.4 |
Aquaponics suitability
Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
One of the easiest and most productive hydroponic Asian greens. EC 1.0-2.0 mS/cm. pH 5.5-7.0. Temperature: 10–25°C (cool-season; more heat-tolerant than lettuce before bolting). Moderate light (DLI 12-18 mol/m2/day). Any hydroponic system works. From seed to baby leaf: 3-4 weeks. Full-sized rosettes: 5-7 weeks. Harvest outer leaves for cut-and-come-again production over 6-8 weeks. The frilly leaf texture makes mizuna a salad mix essential; it adds volume, visual appeal, and a mild peppery accent without overwhelming other flavors. Succession plant every 2-3 weeks. Red/purple varieties ('Red Knight', 'Ruby Streaks') add dramatic color contrast in salad blends. Pest issues are minimal compared to other brassicas. For commercial hydroponic salad mix producers, mizuna is a core component: fast-growing, attractive, and with consistent demand from restaurants and retailers. A top-tier hydroponic crop for any grower.
Verified against: rhs-uk. Last reviewed 2026-05-15.