Cumberland sandwort (Minuartia cumberlandensis) is a federally endangered species native to Kentucky and Tennessee. An in vitro propagation protocol was developed for producing plants for potential outplantings to increase numbers in the wild. Cryopreservation protocols were developed to preserve in vitro lines ex situ. Initial survival of shoot tips through liquid nitrogen exposure ranged from 62–94%, while survival after 10 years in LN ranged from 10–75%. An experimental outplanting of 63 in vitro-propagated plants was undertaken in a rockhouse habitat within the historic range of the species, After 6 years, 12 of the original plants were surviving, but the population had grown to over 200 plants. Survival varied within the rockhouse and appeared to be related to moisture and light variations at the different microhabitats within the site. These results demonstrate that in vitro propagation methods can be used to supplement other conservation efforts with M. cumberlandensis, by supplying plants for outplantings, if needed. In vitro propagated plants can also be used to study microhabitat requirements and to select locations to increase survival of outplanted individuals, without depleting the genetic diversity available for reintroductions.