The latest in seed starting! Styrofoam Floating Trays constantly wick via capillary action to keep seedlings perfectly hydrated. Fill Floating Trays with Gro-Plugs which are pre-shaped spongy plugs of stabilized rooting media that, made of coco fiber and small amount of a synthetic polymer, provide the optimum growing environment (note: Gro-Plugs may not be acceptable for all organic certifiers). Floating Trays can work with other potting mixes, but requires experimentation. To put together your Standard Floating System, order a 1020 Tray, Floating 55-Cell Tray, Gro-Plugs, and either the 2" Lid or 7" Lid. Order all components separately. The 2" Dome Lid fits the 1020 Tray, and extends 2" above the top of the tray.