Salad greens are a multibillion-dollar industry and lettuce is a main component of that industry. Growing lettuce hydroponically usually produces a very clean high-quality product.
Difficulty Level: Beginner
Production Method: Lettuce is usually grown in a deep-water culture(DWC) or nutrient film technique(NFT)
Nutrient Mix: Full Strength
pH: 5.8-6.2
Starting Seeds: Optimum lettuce seed germination temperature ranges from 60-68F. Lettuce seeds need light to germinate, so don’t burry the seed in the media. You can purchase pelletized seed that has been pretreated. The pelletized seed is much easier to handle, doesn’t require light, and you get more uniform germination. I highly recommend it. Seeds can be started in 1-inch rockwool cubes. Water with half strength solution until the first set of true leaves have grown. Next, plant into your DWC of NFT set-up containing full strength solution.
Lettuce Growing Temperature: 45-75F. Optimum growing temperature is 60-65F. When the temperature gets too hot for lettuce, the plant begins to get bitter and starts trying to produce seed. This is called bolting. Keeping the rootzone temperature at 65-70F helps delay bolting brought about by hot weather. It may be worthwhile for a grower to build insulated beds and install a water chiller.
Pollination: No pollination needed
Oxygenation: Circulate and oxygenate 1-2 times per hour, or use air stones that cause significant water agitation.