How to grow Lettuce hydroponically
Lactuca sativa reaches harvest in 35–60 days in a hydroponic system, with a preferred pH of 5.6–7. This guide compiles the operating parameters published by university extension sources for this crop.
Target pH
Maintain reservoir pH at 5.6–7. pH controls how readily the roots can absorb each nutrient; outside this window the plant shows symptoms of deficiency even when the nutrients are physically present in solution.
Measure with a calibrated pH meter at the same time each day and log the reading. Drift of more than 0.3 units over 24 hours usually signals a reservoir change or a nutrient imbalance.
Nutrient schedule
Targets in ppm for the elemental nutrients most commonly tracked in home hydroponics. EC is shown per stage where the cited source publishes it; absence of a stage EC is intentional and not a data gap.
| Stage | EC (mS/cm) | N (ppm) | P (ppm) | K (ppm) |
|---|---|---|---|---|
| seedling | 1.2 | 125 | 31 | 215 |
| vegetative | 1.2 | 125 | 31 | 215 |
Lighting
Daily Light Integral: 17 mol/m²/day. Multiply your fixture’s PPFD by photoperiod hours by 0.0036 to compare against this target.
Photoperiod: 11 hours per day.
Compatible systems
Hydroponic methods that have been documented as workable for this crop in the cited literature.
- Deep Water Culture (DWC)
- Nutrient Film Technique (NFT)
- Ebb & Flow
- Kratky
Sources
All numeric parameters on this page are drawn from the following extension and research sources.
- Cornell CEA Hydroponic Lettuce Handbook (Brechner & Both, 2013) (accessed 2026-04-20)
- UF IFAS Extension HS1422 — Growing Lettuce in Small Hydroponic Systems (accessed 2026-04-20)