Butterhead lettuce

Lactuca sativa

The default commercial hydroponic crop. Uniform heads, short cycle, dense planting.

System

NFT, Kratky, DWC

pH

5.5–6.2

EC

0.8–1.4 mS

Days

28–35

PPFD

200–300

Air temp

18–24°C

Protocol

1. 01Sow into a sterile plug, 18–20°C, even moisture.
2. 02Transplant at day 10–14 when roots show.
3. 03Hold EC near 1.2; tipburn is climate, not more Cal-Mag.
4. 04Harvest whole-head in the morning. Cold-chain immediately.