Napa cabbage
Brassica rapa subsp. pekinensis
Also known as: Chinese cabbage, Wong bok, Wombok, Pe-tsai, Hakusai, Baechu, Celery cabbage, Michihili (cylindrical type)
Quick facts
- Category
- leafy greens
- Difficulty
- intermediate
- Days to harvest
- 60 to 90 days
- Harvest type
- single harvest then replant
- Spacing
- 35 cm between plants
Environment
- Temperature
- 13–21°C
- pH
- 6 to 7
- EC (hydroponic)
- 1.5 to 2.2 mS/cm
- Daily light
- 14 to 18 mol/m²/day
Climate and zones
- USDA zones
- 4 to 9 (winter low around -34°C or warmer)
- Frost tolerance
- frost hardy (handles regular frost)
- Season
- cool (spring and fall crops)
Viable growing environments:
- 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
Napa cabbage works in:
- deep water culture (rafts)
- NFT channels
- 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 (napa cabbage works in the media listed below).
| Medium | pH effect | Water 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 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 | 1.8 |
Companion-growing notes
- Heavy uptake of nitrogen, 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, cool-season hydroponic crop for Asian vegetable production. Large containers or media beds with 15 cm depth. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 12–20°C (critical: above 24°C, the head doesn't form and the plant bolts; below 10°C for extended periods also triggers bolting in some varieties). Moderate light (DLI 12-18 mol/m2/day). From transplant to head harvest: 55-75 days depending on variety. Harvest when the head is firm and dense; squeeze the top gently to check density. Tipburn (internal browning of leaf margins) is a quality issue in some conditions; maintain adequate calcium and good airflow. Mini napa varieties ('Little Jade', 'Minuet') produce smaller heads faster and are better suited to hydroponic systems where space is limited. For commercial growers near Korean or Chinese communities, napa cabbage is a staple product with strong, consistent demand. The autumn kimjang season creates a seasonal demand spike.
Notable varieties
A starting shortlist of cultivars worth knowing about. Not exhaustive: the seed catalogs list hundreds of named varieties. These are the ones home growers commonly choose between.
| Cultivar | Type | Days | Notes |
|---|---|---|---|
| Bilko F1 | hybrid | 60 | Slow-bolting hybrid with high resistance to clubroot and fusarium yellows. The most forgiving napa for hot or variable climates, holds firm 1-foot heads even when picked early. The variety to start with if you've failed at napa before. |
| Michihili | open-pollinated | 70 | Tall cylindrical-head type, the original Chihli selection refined by Ferry-Morse. Less heat-tolerant than modern hybrids but the traditional choice for Asian markets. Heads can reach 18 inches tall with a tapered top. |
| Wong Bok | open-pollinated | 75 | Squat barrel-shaped heads, the classic supermarket napa shape. Mild sweet flavor, stores well in the fridge for weeks once cut. More bolt-prone than Bilko, plant for fall harvest. |
| Minuet F1 | hybrid | 55 | Johnny's Selections-vetted Korean hybrid (2000). Small dense heads, useful for cramped spaces or short shoulder seasons. Slower to bolt than the heirlooms; sized for one or two meals rather than a kimchi batch. |
| Blues F1 | hybrid | 65 | Bolt-tolerant pekinensis hybrid often grown as a spring crop where most napa would flower. Slightly looser head than Bilko but more uniform across a transplanted block. Common in commercial CSA production. |
Plan a setup with Napa cabbage
Verified against: rhs-uk, kitazawa-seed-co, korean-rural-development-administration, u-florida-ifas. Last reviewed 2026-05-15.