The Super Sprouter? Root Raft? floating plug tray is designed to be a self-watering starter tray. Root Raft? includes a 10 x 20 in tray for holding water and a styrofoam 55-site floating insert loaded with Super Sprouter? custom-blended and custom-sized grow plugs. Mother Earth? BioChar is added to this exclusive formulation. No worries about watering?moisture is automatically wicked through the plugs. Just fill the tray and walk away. If you desire a mini greenhouse effect, you can use any of the Super Sprouter? domes to get the job done. Domes sold separately.