Common problems for Christmas Cacti are dropping of unopened buds, lack of flowering and root rot. Causes for problems include sudden light changes, dried soil or excessive watering.
Excessive budding or drying out of soil often causes dropping of unopened buds. Interruption of long dark nights from indoor lighting causes lack of flowering. Street lights or car lights are other sources of interruption. Over watering or damage to plants at the soil line cause root rot. Fungicide application is a difficult remedy because each type of root rot requires a specific treatment. For prevention, water the plant only when the soil is slightly dry.