Meristem culture may or may not be combined with thermotherapy (>35°C) of the mother plant (as in the case of Narcissus where pre-conditioning of the bulbs is required at 30 °C for 9 weeks followed by 50 °C hot water treatment for up to 1 hour) and the inclusion of chemical anti-viral agents (e.g. virasol) in the medium.

The smaller the meristem the more chances to eliminate a specific virus or bacteria.