DOC №049SEC: PLANTSREV: 2026-05-15AUTHORED
How to Grow Lettuce Hydroponically
Lettuce is the easiest hydroponic crop — fast, forgiving, and high-yield. This guide covers pH, EC, light, harvest timing, and the best system for every variety.
BY ROOTLESS FARM
Quick answer
Hydroponic lettuce reaches harvest in 28–35 days from transplant when grown at pH 6.0, EC 1.0, DLI 14 mol/m²/day, and water temperature 18–22 °C. Deep Water Culture, NFT, and the Kratky method are all suitable; DWC is most forgiving for beginners.
Conditions
| Parameter | Value |
|---|---|
| pH | 5.5–6.5 (6.0 ideal) |
| EC | 0.8–1.2 mS/cm |
| Air temp | 15–22 °C |
| Water temp | 18–22 °C |
| Humidity | 50–70% |
| DLI | 14 mol/m²/day |
| Photoperiod | 14 h |
| Spacing | 20 cm |
Best system
Deep Water Culture for hobbyists; NFT or raft for commercial. Kratky for off-grid / no-pump setups.
FAQ
3 entries- Q01How long does hydroponic lettuce take?
- 28–35 days from seedling transplant to harvest, depending on variety and DLI.
- Q02What pH and EC for lettuce?
- pH 5.5–6.5 (ideal 6.0); EC 0.8–1.2 mS/cm (~560–840 PPM at the 700 scale).
- Q03Why is my lettuce bolting?
- Air temperature above 24 °C or long days trigger bolting. Drop temps to 18–20 °C and shorten photoperiod to 12 h.