Hydroponic Raft systems are methods of solution culture where plants are supported by a sheet of lightweight material, typically polystyrene, that floats on the surface of a large pond of nutrient solution. Seedlings are usually raised in a separate nursery area, sown into either blocks of inert propagation media like stone wool or into small tubes or lattice pots of substrate. Once the seedlings have reached an optimal size, they are inserted into holes cut into the floating rafts and set adrift on the nutrient pond. Roots develop down into the nutrient solution, which supplies mineral elements and dissolved Oxygen for root respiration.