Getting a Christmas cactus to bloom may be difficult. Cool temperatures or long nights are needed to induce flowering. Blooming will occur when night temperatures are about 55 degrees F and day temperatures are below 65 degrees F.
Flowering is related to day length and night temperatures. The temperature range for flower bud development is 55 to 60 degrees F for a six-week period. If temperatures remain in this range, they will develop buds regardless of day length. If temperatures get above that range, the plant will need 13 hours of uninterrupted darkness each night. This can be accomplished by placing the plants in a completely dark room or covering them for the recommended time (or longer) with a dark piece of cloth. The plants can also be kept in total darkness in a closet till buds develop.
To produce holiday blooms, you will need to start this process in late September to mid-October. During flower bud formation, stop fertilizing, and only water enough to keep the leaves from becoming shriveled. Once buds do form, then you can keep the plant in normal light and temperatures. Keep it evenly moist and fertilize every other week with a mild fertilizer solution. A general schedule for maintaining a Christmas Cactus is as follows:
1. January - Flowering.
2. February to March - Resting (55 degrees F, infrequent watering).
3. April to May - Water thoroughly when potting mix begins to dry out.
4. June to August - Place outdoors in a shady spot. Bring inside at the end of August.
5. September to October - Plant prepares to flower. Reduce the length of the daylight hours. Keep on the dry side and cool (55 to 60 degrees F) until flower buds form. Then increase water and temperature.
6. November to December - Flowering. Water normally. Temperatures no less than 55 degrees F.
