In general, seeds of the genus flex have immature embryos at the time of ripeness, necessitating a period of after-ripening before germination will occur. Experiments performed at the Arnold Arboretum by former propagator Alfred Fordham in 1963, and again in 1973, suggest that the best results are obtained by sowing the seed in a warm greenhouse and then waiting for germination to occur. After eight months, 57 percent of the freshly collected, cleaned seeds germinated. — Dirr, Michael A., and John H Alexander III. “Ilex Glabra-The Inkberry Holly." Arnoldia 51, no. 2 (1991): 16–22.