Schlumbergera x buckleyi doesn't sound like such a pretty plant, but Christmas cactus and their relatives, the Thanksgiving cactus (S. truncata) and Easter cactus (Hatiora gaetneri), are among the most beautiful of holiday plants. Hailing from the mountainous jungles of Brazil, they aren't true cacti like the ones you see in Western movies, but epiphytes enjoying the high life among the tree branches. Providing the plants with conditions that mimics their natural environment helps them survive and thrive in your home.
Christmas cactus prefer bright, diffused light. East or west-facing windowsills are best. Too much sunlight burns the leaves, and most southern exposures provide too much light for their taste.
Christmas cactus produce flower buds when the cycles of light and darkness tip into the winter cycle, with 12 or more hours of darkness signaling the plants that it is time to produce buds. Most Christmas cactus flower during the holidays have been tricked into setting buds by the clever use of artificial lights and timers. After the first year, they are more likely to bloom closer to Thanksgiving unless you can mimic their natural cycle of dark and light more closely than nature provides in the northern hempisphere.
If you need to repot your Christmas cactus, you can use either a sterile potting soil mix or a mix for succulent houseplants purchased from your local garden center. Christmas cactus need rich, well-drained soil, so be sure that the container chosen for your plant has drainage holes punched through the bottom of the pot. Some experts recommend adding leaf mold or compost to the container, but garden compost carries unwanted pests along with desired nutrients. Commercial fertilizers may be helpful in replicating the nutrient-rich soils Christmas cactus thrive on in the wild.
Watering can is tricky with Christmas cactus. While they are drought-tolerant, they do not like their soil to get completely bone-dry like true desert cacti. Water Christmas cactus throughout the year when the soil is dry to the touch. To help your Christmas cactus set bud for the holidays, make sure to water more frequently during the summer months, but cut back on the watering in October. Withholding water during October helps trigger the plant's flowering mechanism, and it is more likely to produce abundant flowers for the holidays.
The best time to fertilize Christmas cactus is in the spring. When you see new growth appearing at the end of the stems, it's time to fertilize your Christmas cactus. Use a liquid houseplant fertilizer of 10-10-10 according to the package directions. Fertilize Christmas cactus for only a few weeks during the spring.
Encouraging Your Christmas Cacti to Flower
One of the challenges many Christmas cactus aficionados face is getting their plants to bloom again in subsequent years. Most of the plants you see flowering during the holiday season at your local garden center were grown under artificial lights and perfect conditions in a professional grower's greenhouse. To coax plants to set buds, growers manipulate light, temperature and moisture levels to fool the plants into thinking it's spring. You can accomplish the same thing at home by making some simple changes to your plant's environment a few weeks before the holidays.
First, if you bring your plants outside during the summer months, make sure to bring them indoors by mid September. Place them in bright, indirect light.
Temperature fluctuations also signal to your plant that it's time to produce flowers. Keep daytime temperatures in the upper 60s to mid 70s, and nighttime temperatures in the low 60s to mid 50s. Many people simply leave their plants next to an open window during the autumn months to give Christmas cactus the proper temperatures.
Keep your Christmas cactus evenly watered throughout the fall, never letting it get too dry. Once it sets buds, be sure to keep the soil evenly moist; big changes in soil moisture can cause the plant to drop its buds before they open.
Some people trick their Christmas cactus into setting bud by keeping the plant in total darkness for a week or two until it sets bud. You can do this by placing the plant in a closet or basement. If you'd like to try this technique, time it for the last week of September through the first week or two of October for best results. Once the plant develops buds, move it back into a well-lit room and care for it as you normally would.
Problems with Christmas Cactus
Christmas cactus are surprisingly hardy. They suffer from a handful of problems, however.
- Bud Drop: If your Christmas cactus drops its buds before they open, there are several possible causes. If your plant is too close to a heating vent, hot drafts can cause bud drop. So can cold drafts if the plant is near an open window or subjected to drafts from doors opening and closing throughout the day. Other possible causes are lack of potash in the soil and uneven moisture. Use a weak liquid houseplant solution to help your plant obtain the proper nutrients, and watch your watering schedule, especially in the weeks leading up to the time your plant sets buds.
- Insects: Two insects that can sometimes plague Christmas cactus are mealybugs and scale. Hand-pick mealybugs off the plant or use an alcohol pad to swab them with rubbing alcohol to kill them. Insecticidal soaps treat both scale and mealybug.
- Over-watering: By far the more common problem is over-watering Christmas cactus. The stems tend to shrivel if the plant is watered too much, which leads people to mistakenly think the plant is thirsty. This perpetuates the cycle of over-watering until the plant virtually drowns. Too much water also encourages mealybugs to proliferate, which helps weaken the plant further. To prevent over-watering, use the finger test to determine when plants need water. Simply stick your finger into the soil to the first joint; if the soil is dry, the plant s needs water.
With a little TLC, your Christmas cactus can not only survive the holidays but thrive for generations to come.