Mibuna
Brassica rapa var. nipposinica
Also known as: Mibu greens, Japanese mustard greens
Quick facts
- Category
- leafy greens
- Difficulty
- beginner
- Days to harvest
- 30 to 50 days
- Harvest type
- continuous production over weeks or months
- Spacing
- 20 cm between plants
Environment
- Temperature
- 4–22°C
- pH
- 6 to 7
- EC (hydroponic)
- 1.2 to 1.8 mS/cm
- Daily light
- 12 to 18 mol/m²/day
Climate and zones
- USDA zones
- 3 to 10 (winter low around -40°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
Mibuna works in:
- deep water culture (rafts)
- NFT channels
- media bed (ebb and flow)
- wicking bed
- soil bed
- vertical / aeroponic tower
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 (mibuna works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Perlite (Expanded volcanic glass) | neutral / inert | very low | low |
| 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 | 2 | 1 | 1 | 0.8 |
| 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
An easy, fast hydroponic green with excellent cut-and-come-again performance. EC 1.2-2.0 mS/cm. pH 5.5-7.0. Temperature: 10–25°C (cool to moderate; more bolt-resistant than lettuce in warm conditions). Moderate light (DLI 12-18 mol/m2/day). NFT, DWC, raft, or vertical systems. From seed to baby leaf: 3-4 weeks. Full-sized leaves: 5-7 weeks. The thin, strap-like leaves add a unique textural element to salad mixes, distinct from the frilly texture of mizuna. Harvest outer leaves for continuous production; each planting can produce for 6-8 weeks before bolting. Succession plant every 3 weeks. The peppery flavor is milder than arugula and slightly stronger than mizuna, filling a useful middle ground in salad mix flavor profiles. Pest issues are minimal. Mibuna is virtually unknown at Western retail, which represents a novelty opportunity for growers selling at farmers' markets or to restaurants. For Asian salad mix production, the combination of mizuna (frilly, mild) and mibuna (strap-shaped, slightly peppery) creates a visually and gastronomically interesting product.
Verified against: kitazawa-seed-co, kyoto-prefectural-u, rhs-uk. Last reviewed 2026-05-15.