Gai lan
Brassica oleracea var. alboglabra
Also known as: Chinese broccoli, Kai lan, Chinese kale, Jie lan
Quick facts
- Category
- leafy greens
- Difficulty
- beginner
- Days to harvest
- 60 to 80 days
- Harvest type
- cut leaves, plant regrows for repeated harvests
- Spacing
- 25 cm between plants
Environment
- Temperature
- 12–26°C
- pH
- 6 to 7
- EC (hydroponic)
- 1.5 to 2.5 mS/cm
- Daily light
- 14 to 20 mol/m²/day
Climate and zones
- USDA zones
- 4 to 10 (winter low around -34°C or warmer)
- Frost tolerance
- tolerates light 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
Gai lan works in:
- 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 (gai lan works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| 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 | 0.8 |
| vegetative | 3 | 1 | 2 | 2 |
Companion-growing notes
- Heavy uptake of calcium. Co-grown crops with the same demand will end up deficient even at "correct" EC. Plan around this in shared reservoirs.
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
A fast, productive hydroponic crop well-suited to Asian vegetable production. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 15–25°C (cool to moderate; tolerates heat better than regular broccoli but bolts faster above 28°C). Moderate light (DLI 14-20 mol/m2/day). NFT, DWC, or media bed systems work. From seed to harvest: 5-7 weeks for baby gai lan, 7-10 weeks for full-sized stems. Harvest the main stem with 2-3 leaves when the first flower buds appear but before they open (open flowers indicate overmaturity and tougher stems). After the main stem is cut, side shoots develop and provide 2-3 additional harvests. The thick stem should be peeled if the outer layer is fibrous (split the base; if it's stringy, peel). Caterpillars and aphids are common brassica pests; BT spray and careful monitoring manage them. For commercial hydroponic growers near Chinese communities, gai lan is a consistent seller with strong demand. Succession plant every 2-3 weeks for continuous supply.
Verified against: rhs-uk, university-of-florida-ifas. Last reviewed 2026-05-15.