Improved propagation methods greatly benefit conservation of rare cycads. Appropriate substrate conditions, especially excellent root aeration, are crucial to successful cultivation of most cycads. Typical cycad substrates include substantial portions of organic materials that will decompose over time, reducing drainage and increasing water retention. In this study, two inorganic substrates, arcillite (Turface® MVP®) and coarse silica sand, and one mixed cycad substrate (with organic and inorganic components) were evaluated for germination and growth of three rare Zamia species: Z. fairchildiana L.D. Gómez, Z. cunaria Dressler & D.W. Stev., and Z. aff. portoricensis Urb. over a period of 14 months from seed sowing. Substrate type affected leaves per seedling and leaf length. These factors also varied by species as did taproot length and germination rate. There were also significant interactions between substrate and species for caudex diameter and leaf variables, likely reflecting ecological differences among the species, two of which are from rainforest habitats and one from dry forest. All three substrates performed adequately for germination, survival, and growth of Zamia. Turface® and possibly the silica sand likely require additional watering to improve their performance as cycad substrates.