Komatsuna
Brassica rapa var. perviridis
Also known asJapanese mustard spinach · Tendergreen · Mustard spinach
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 4–11 (winter low around -34°C)
- Frost
- frost hardy
- Season
- cool (spring/fall)
Growing systems
Root mass: light.
Growing media
| Medium | pH effect | 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 | high | high |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.8 |
| vegetative | 3 | 1 | 2 | 1.7 |
Companion-growing notes
- Heavy uptake of calcium. Co-grown crops with the same demand will end up deficient even at "correct" EC.
Aquaponics suitability
Compatible
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 excellent hydroponic leafy green combining the ease of lettuce with the nutritional density of kale. EC 1.2-2.0 mS/cm. pH 5.5-7.0. Temperature: 10–28°C (wide range; one of the few brassica greens that produces well in both cool and warm conditions without bolting quickly). Moderate light (DLI 12-18 mol/m2/day). NFT, DWC, raft, or vertical systems. From seed to baby leaf harvest: 3-4 weeks. Full-sized harvest: 5-7 weeks. Succession plant every 2-3 weeks. Cut-and-come-again harvesting works well: take outer leaves while the center continues producing. The mild flavor makes komatsuna more versatile than spicier Asian greens like mustard or mizuna: it can be used raw in salads, wilted in soups, or stir-fried. Pest issues are minimal compared to other brassicas. For hydroponic growers who want a productive, fast, versatile Asian green with wide temperature tolerance, komatsuna is a top choice. Less commonly available at Western retail, which creates an opportunity for growers serving Japanese or health-food markets.