 Seedlings are germinated in cubes (such as rockwool, oasis, or other media) and then transplanted into the rafts.Plants may be re-spaced during the growth period (higher density at first, and lower density later).The nutrient solution is oxygenated through air pumps or recirculation, and water is chilled to a temperature between 18-24C in order to maintain proper dissolved oxygen concentration, which is crucial to plant growth.