The Christmas cactus (Schlumbergera bridgesii) is native to the jungles of South America, and available in a wide variety of colors including red, purple, oranges, pinks and creams. Its pendulous stems make it a great plant for hanging baskets.
While the Christmas cactus can adapt to low light, more abundant blooms are produced on plants that have been exposed to high light. While indoors, keep your plants in a sunny location. You can move your Christmas cactus outdoors in summer, but keep it in a shady or semi-shady location. Too much direct sunlight during the summer months can turn the leaves yellow, or even burn the leaves.
The Christmas cactus prefers warm temperatures. Good, vigorous growth occurs at temperatures between 70 to 80 degrees F during its growing season from April to September. However, evening temperatures of 55 to 65 degrees F are best for flower bud formation. When you move your plant indoors in fall, keep it away from heat vents, fireplaces or other sources of hot air, especially once flower buds are set. Continuous warm temperatures - especially above 80 degrees F - can cause the flower buds to drop.
The Christmas cactus also requires thirteen hours or more of continuous darkness each day before flowering will occur. This occurs naturally in fall. Street lights, car lights or indoor lighting can disrupt the required dark period, causing a lack of flowering.
The plant is not a true cactus and is not quite as drought tolerant as the name infers. However, it is a succulent plant and can tolerate some drying. Water thoroughly when the top half of the soil in the pot feels dry to the touch. During the summer, water so that the soil is always slightly moist. The plant does not tolerate wet, waterlogged soil conditions, especially during the dark days of winter. When fall arrives, water the plant only well enough to prevent wilting.
The Christmas cactus flowers best when kept somewhat potbound. Plants should be repotted in spring every two or three years, or whenever the pot is filled with roots and the soil no longer holds water and nutrients.
Fertilize your Christmas cactus with a soluble houseplant fertilizer every three to four weeks when new growth starts in early spring, and throughout the summer. Reduce the fertilizer during the fall and early winter. During flower bud formation, stop fertilizing and only water enough to keep the leaves from becoming shriveled.
Prune your Christmas cactus after blooming to encourage the plant to branch out. Remove a few sections of each stem by pinching them off with your fingers or cutting with a sharp knife. You can start new plants by rooting the stem tips in moist potting soil.
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.