It is known that two in five plants, and one in three trees, are threatened with extinction and thus, botanical gardens around the world play a key role in ex situ preservation of plant genetic resources. The traditional conservation methods, seed and field banks, are not efficient (high cost of maintenance, risk of loss) for the long-term conservation of some plant species. Therefore, lately some botanical gardens, such as The Huntington, are using cryobiotechnology (i.e., micropropagation and cryopreservation) as an alternative to secure germplasm collections. The projects often focus on the optimization of tissue culture methodologies as well as the design of cryopreservation protocols, which aim the middle- (in vitro repositories) and long-term (cryobanks) storage of high priority plants. In addition, the strategies from collecting plant material to rooting and acclimation before the plants can go back to the field conditions are developed. However, additional efforts are still needed for many wild plant species in peril. Case studies including aloes, agaves, magnolias, avocado and oaks are discussed.