How to Float & Grow Lettuce

Fill a deep-water-culture tub with the prepared nutrient solution. This is normally 1 to 2 inches from the top of the tub.

Connect the air stone to the air line and place the stone in the bottom of the tub. Connect the other end of the air line to the air pump. This provides oxygen to the growing lettuce.

Cut several 3-inch holes in the Styrofoam sheet. The number of holes depends on the size of the Styrofoam. Don't cut too close to the edge of the Styrofoam, since that weakens it. Leave at least 3 inches between the holes.

Float the Styrofoam raft on top of the nutrient solution. The raft is the platform that holds the net pots while the lettuce is growing.

Soak the rock wool cubes in plain water. Use one cube for each hole in the raft. Rock wool is an inert growing medium that is excellent for starting and growing plants.

Place one rock wool cube in each net pot. Both rock wool cubes and net pots are available inexpensively from hydroponic supply stores. Net pots allow the water to pass freely through them, keeping the plants' roots immersed in the nutrient solution at all times.

Seed the rock wool with several lettuce seeds. If the cube has a hollow in the top, place the seeds in there. Otherwise, sprinkle the seeds on top of the rock wool cube. Thin to the single strongest seedling once the plants emerge.

Fill the net pot with clay pellets. This provides support to the rock wool as well as to the plants once they begin to grow. Do not bury the seeds with the pellets. Use pea gravel instead, if you prefer, but make sure it is clean.

Set one net pot in each hole in the raft to complete the setup. The pots will extend down through the raft and into the nutrient solution. The lettuce floating in your DWC system will grow quickly and is ready for harvest in a month or less.