Tatsoi
Brassica rapa subsp. narinosa
Also known asSpoon mustard · Spinach mustard · Rosette pak choi · Tat soi · Tah tsai
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 3–10 (winter low around -40°C)
- Frost
- very hardy (survives deep cold)
- 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 | 0.7 |
| vegetative | 3 | 1 | 2 | 1.6 |
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
A fast, easy, cold-tolerant hydroponic green. EC 1.2-2.0 mS/cm. pH 6.0-7.0. Temperature: 5–24°C (one of the most cold-tolerant Asian greens; produces through winter). Moderate light (DLI 12-17 mol/m2/day). Any hydroponic system works. From seed to baby leaf: 3-4 weeks; full rosettes: 5-7 weeks. Harvest whole rosettes or outer leaves for cut-and-come-again production. The flat rosette shape makes efficient use of growing space, and the dark, glossy leaves look attractive in salad mixes. Succession plant every 2-3 weeks. Flea beetles are the main pest. Tatsoi's cold tolerance makes it one of the best crops for winter hydroponic production in minimally heated greenhouses, and baby tatsoi adds visual contrast and a mild Asian-green flavour to commercial salad mixes.