An excellent alternative for germinating seeds and root development. The Flexiplugs and Fleximats are comprised of 90% organic materials in the form of composted bark and peat, held together by a non phototoxic binder that produces a sponge-like plug cell or cube. The plugs have about 50% fixed capillary pores that retain water while the other half of the pores do not. This high porosity is the key to a healthy root system and will not compact, providing good aeration throughout the growth cycle. Designed for most types of plant propagation from seeds or cuttings. Ideal for starting seeds indoors. This set is comprised of a solid bottom tray with a self supporting 55 cell polystyrene tray filled with 55 Flexiplugs that have pre-dibbed holes. It couldn't get any easier- drop a seed into each hole and water. You'll have the perfect environment for your seedlings to form a healthy root system because each sponge-like plug will not compact, thus providing good aeration during the growth cycle. The trays can be reused year after year and if you prefer, our propagating dome (H117D) fits this tray set perfectly.