Bok choy
Brassica rapa subsp. chinensis
Also known asPak choi · Chinese cabbage · White cabbage · Pak choy · Buk choy · Bai cai · White cabbage (Chinese) · Chinese white cabbage
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 4–9 (winter low around -34°C)
- Frost
- tolerates light frost
- 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 | 1.8 |
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, rewarding hydroponic crop, well suited to Asian-vegetable production. Hold EC around 1.5-2.5 mS/cm and pH 6.0-7.0. It is a cool-season crop, best at 15–24°C, and bolts quickly above about 26°C. Keep light moderate, 12-17 mol/m2/day. Baby bok choy is ready in three to four weeks from seed, full-sized in six to eight, in NFT, deep water culture, raft and vertical systems, and the compact rosette uses space efficiently. Sow every two to three weeks for a steady supply, and in warm conditions choose bolt-resistant varieties such as Mei Qing Choi or Win-Win. Feeding is moderate on a standard leafy-green mix. Flea beetles and caterpillars (cabbage loopers, diamondback moth) are the main pests in open greenhouses, controlled with row cover or a Bacillus thuringiensis spray. Baby bok choy is a high-value, fast-turnover crop, and in aquaponics it grows noticeably faster on the nutrient-rich water than in plain hydroponics.