Butterhead lettuce
Lactuca sativa var. capitata
Also known asBibb lettuce · Boston lettuce · Butter lettuce
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 | 0.6 |
| vegetative | 3 | 1 | 2 | 1.2 |
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
The standard commercial hydroponic lettuce alongside loose-leaf types. EC 0.8-1.5 mS/cm. pH 5.5-6.5. Temperature: 15–22°C (cool-season crop; above 24°C, bolting begins and leaves become bitter). Moderate light (DLI 12-17 mol/m2/day; excessive light causes tipburn and accelerates bolting). From seed to harvest: 5-7 weeks as heads, 3-4 weeks as baby leaf. NFT, DWC, and raft systems are the standard commercial setups. Tipburn (calcium deficiency at the leaf margins of inner leaves) is the most common quality issue; caused by insufficient calcium transport to fast-growing inner leaves in still air. Improve airflow around heads with fans, and maintain adequate calcium in the nutrient solution. 'Rex' and other tipburn-resistant varieties are preferred for commercial production. For the living lettuce market, harvest the entire plant with root plug attached and package in clamshells. Succession plant weekly for continuous production. Butterhead lettuce is the highest-value lettuce type per head ($2-4 retail per living head), making it the economic foundation of many small commercial hydroponic operations.