Grow Plugs
Grow plug is a composition of different growing mediums like peat and other organics. They are soilless propagation mediums for plant growth. They come in different quantities and different compositions. You can choose what you need for your Hydroponic setup. ZenHydro lists Rockwool plugs and hydroponic starter plugs. All you need is to get one and insert the plugs directly into the cells of your growing tray.