Ex situ conservation is an essential tool for combatting biodiversity loss. The Fern Lab at the National Botanical Garden in Kaua‘i was established with the goal of propagating some of the world’s most imperiled plants, including 22 Hawaiian species that are considered endangered or critically endangered by IUCN. We provide basic protocols for fern propagation and maintenance with an emphasis on sterile technique. We describe the facility design, tools and materials needed, a step-by-step guide for sterilizing media, and protocols for maintaining healthy cultures from spore to sporophyte. Because the NTBG Fern Lab handles a large number of threatened and endangered species, special care is taken to avoid contamination; however, the techniques presented here could be employed or adapted by professionals or hobbyists alike.