Lettuce is a popular crop for aquaponics and grows with relative ease. Most varieties of lettuce can grow within an aquapons system with iceberg, butterhead, Romaine and loose leaf lettuce being the most popular.
Lettuce is an ideal crop during the winter, growing well temperatures of 3-12°C at night and 17-28°C during the day. While a pH of 5.8-6.2 is ideal, lettuce can still grow with a pH of up to 7.
Lettuce seedlings are ready to be transplante once they have 2-3 true leaves, which usually takes about three weeks. Fast growth tends to occur when system nitrate levels are high. Higher survival rates occur in transplants when seedlings are exposed to a combination of colder temperatures and direct sunlight for 3-5 days before tranplanting (plant hardening) and transplanting them in warm water with light shading for the first 2-3 days to avoid water stress.
As soon as the heads of lettuce have reached the desired size, harvesting can begin. Market weight and size varies depending on location and buyer type, but the market weight is usally around 250-400g.