First, it is important to use Petri dishes that are filled properly. Because C-Fern cultures are maintained for a prolonged period of time it is necessary to fill each dish three-quarters full with Basic C-Fern Nutrient Medium. (See How much medium should I pour into the culture dishes?).
Another factor may be the culture environment in which the dishes are kept. Environmental growth chambers often have a constant airflow which accelerates premature drying out of cultures. In this situation or other situations where drafts are a problem, to reduce evaporation of media, the cultures can be kept within Culture Domes that are firmly secured.
C-Fern Growth Pods also may be a solution to culture drying as well as maintenance and regulation of optimal temperature for C-Fern growth. C-Fern Growth Pods can be assembled from inexpensive and easily obtainable materials.