As the Christmas season rolls around again, I fondly remember the large Christmas cactus that my mother had, and I always enjoyed its beauty especially around Christmas when it was in full bloom. This houseplant has been a favorite since Grandma or Great Grandma’s day. It’s not unusual for a single plant to be passed down from generation to generation because they’re long-lived and rather easy plants to grow. I always wondered how my mother got the Christmas cactus to come into full bloom during the holiday season. To me as a small boy, it was another miracle of Christmas, just like how did Santa get down our chimney when the fire was blazing without getting burned.
The Christmas cactus is a member of the Zygo-cactus family and native to Central and South America. Although these plants are called cacti, they are not at all like the common desert cactus. These plants, like orchids, are called epiphytes and are found in similar environments as orchids. They are most often found in the forks of tree limbs where they grow in decayed leaves and other natural debris that tend to accumulate there. Being tropical cacti, their cultural requirements are totally different from true desert cacti.
In September and October, you need to make sure that your Christmas cactus is kept in a cool room where temperatures remained around 50 degrees, give or take a few degrees but be sure not to expose them to freezing temperatures. Another key to success is that they be kept in a room where no artificial light will be turned on at night.
The key to getting Christmas cactus to flower during the holiday season is the proper light exposure, correct temperatures and limited watering. This means that during the fall months, the Christmas cactus should be placed in a spot where it receives indoor indirect bright light during the daylight hours but total darkness at night.
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Because the Christmas cactus is a tropical plant, it will require watering on much the same basis as any other type of tropical plant. A good procedure to follow is to water the plants thoroughly and then allow about the top inch of soil to dry before watering again. During the fall and winter months, water less frequently in order to get them to bloom.
The Christmas cactus requires higher humidity. This can be accomplished by creating a humidity tray, which is done by filling a waterproof saucer with gravel, then adding water halfway up the gravel. Place the cactus on the gravel surface.
Never place the plant near a door that opens and closes to the outside. Likewise, keep it away from heating ducts or near the fireplace or drafty areas. In late October or early November, fertilize with a 0-10-10 type liquid fertilizer. A second application of this fertilizer can be made in February. During the growing season from April through September, fertilize the plants with an all-purpose liquid houseplant type fertilizer. The fertilizer you use should have a nitrogen ratio of no higher than 10 percent.
One of the frustrating things that can happen to Christmas cactus is after the flower buds have developed they drop off the plant. Bud drop is usually caused by over-watering, lack of humidity or insufficient light.
After the Christmas holiday season, the Christmas cactus should be given a 30-day rest period. Again place it in a cool room and provide limited water. Don’t worry if it loses a few leaves or joints and appears weak during this rest period. The best time to pinch, prune or shape a Christmas cactus is when the new growth begins in March or early April, and the best time for repotting a cactus is in February, March or April. However, the plant will flower best if it’s kept in a container where it’s pot-bound. Finally, if your Christmas cactus is given proper care and is placed in the right location, it’s not unusual for it to flower several times throughout the year.
Bill Lamont is a professor emeritus in the department of plant science at Penn State and can be reached by email at firstname.lastname@example.org.