Butterhead lettuce has excellent potential as a hydroponic crop in India. This variety of lettuce has a distinct sweetness in the taste with the unique buttery texture.
Unlike other hydroponic crops like tomato and cucumber, lettuce has good potential to grow under low light levels and in cold climatic conditions. That is why lettuce is preferably grown during the winter months.
It is crucial to use selected, well-adapted crop cultivars to get a high yield as well as better quality. The most suitable cultivars determined by their head size, texture, appearance, speed of development, flavor, susceptibility to biotic (insect and diseases) and abiotic (low light, heat and cold) stresses.
Production of Seedlings
Rockwool is the most commonly used germination media in hydroponics. The seeds get placed in the media for the germination process. The germination media should soak with water having a pH of 5.5.
The butterhead lettuce seeds require a temperature between 18 °C to 20 °C. The germination tray should be covered with a transparent lid to ensure that they won't lose water.
The seedlings get watered every day for seven days, and after that, they watered every 2-3 days with 100 ppm N.
After four weeks of watering the seeds, they have reached about 10 cm in height and have 5-6 leaves. At this stage, seedlings should get transplanted into the hydroponic system.
Growth Requirements
Temperature Requirements for Butterhead Lettuce
All lettuce varieties grow well in cold climatic conditions. The optimum temperature for Butterhead lettuce is between 20 °C to 23 °C when the temperature goes higher bolting starts, and bolting changes the lettuce taste from sweet to bitter.
Lettuce prefers the night temperature between 15 °C to 18 °C for proper growth.
Maturity Period
Lettuce is a rapidly growing crop. Butterhead lettuce's crop cycle is shorter than other lettuce varieties. Butterhead lettuce takes around 45-55 days to get fully matured.
Light Requirements
Lettuce crops can perform well even in low light conditions as they are not much a light-demanding crop.
Moderate sunlight for about 10 to 14 hours a day is sufficient for the growth of Butterhead lettuce. More sunlight can cause bolting, which changes the biochemical composition of the leaves.
Type of hydroponic systems adapted for Butterhead Lettuce
The lettuce crops can grow well in different hydroponic systems, but the most commonly adopted system is the Nutrient Film Technique (NFT) system.
Before choosing the type of hydroponic system, keep in mind that it should represent the most effective use of nutrients and growing space in your hydroponic farm.
NFT Hydroponic system
The Nutrient Film Technique (NFT) system uses food-grade PVC pipes as a growing structure in which the nutrient solution recirculated by using a pump.
Each NFT system is customizable according to the plant requirements. For Butterhead lettuce standard NFT system consists of growing channels that are 3-4 m long, 6.0-6.5 cm wide, and 6.35 cm deep.