Christmas cactus (Schlumbergera bridgesii) provide a welcome burst of red, pink, white, orange or purple flowers in winter, which makes them classic holiday houseplants. They flower so abundantly, you will want to see them re-bloom year after year. Christmas cactus grow outdoors in U.S. Department of Agriculture plant hardiness zones 9 through 11 but are usually grown as houseplants.
Stop fertilizing the plant and pinch back stems in June to encourage new growth and flower terminals. With your fingers, twist off one or two segments of each stem. Do this only once. It creates new branching and new bud development for holiday blooms. In September pinch back any segment that is less than 1/3 inch long. These short, immature segments will not produce flower buds by bloom time.
Water, Light and Temperature
A Christmas cactus needs low temperatures between 60 and 68 degrees Fahrenheit and darkness to start its bloom cycle. Begin in September to provide the plant with these conditions. Place your cactus in an area of the house that remains at 60 F during the night and receives only nine to 10 hours of light during the day. The plant needs 14 hours of darkness each day to begin bud production.
Continue to water weekly until the flower buds begin to develop. Reduce the watering to every other week as the buds grow. Allow the cactus to dry out between waterings.
Check how damp the soil is by inserting a finger up to the first knuckle to gauge dryness. The soil should feel slightly dry but not parched.
Enjoying the Flowers
Move the Christmas cactus to its display area when the flowers have developed enough to begin to open. Make sure the plant continues to receive bright, indirect light and the room temperature does not go above 70 F. A warm room causes flowers to fade and drop off quickly.
When a Christmas cactus is given enough darkness and low temperatures beginning in September, it will bloom successfully at the end of December. The flowering period lasts seven to eight weeks when temperatures are kept under 70 F.