Our SUN GRO propagation mix is a growing medium that is perfectly designed for seed tray cell packs for a wide variety of plant types. It has fine particle size and has high water retention. Our mix contains Fine Sphagnum Peat Moss, Fine Perlite, Dolomite Lime, Long-Lasting Wetting Agent, and RESiLIENCE; a beneficial plant substance that may make plants stronger.