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What to know about the 3 types of holiday cacti

It’s not unusual for a single Christmas cactus plant to be passed down from generation to generation because they’re long-lived and rather easy plants to grow.
It’s not unusual for a single Christmas cactus plant to be passed down from generation to generation because they’re long-lived and rather easy plants to grow. TNS

I remember the large Christmas cactus that my mother nurtured and how I always enjoyed its beauty, especially around Christmas when it was in full bloom. This houseplant has been a favorite plant since Grandma’s day and 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.

As I later learned from my good friend George Hochmuth, professor emeritus, University of Florida, there are actually three different holiday cacti: the Thanksgiving cactus (Schlumbergera truncata), the Christmas cactus (Schlumbergera bridgesii) and the Easter cactus (Rhipsalidopsis gaetneri). The problem is they all look alike.

The Schlumbergera species are native to the tropical forests of Brazil, while the Rhipsalidopsis species is native to the natural forests of Brazil. Although these plants are called cacti, they are not at all like the common desert cactus. These three species of cactus are members of the group of cacti called leaf cacti and the plant bodies are flattened and the leaves are actually stems. The flowers are produced from notches in these stems or from the tips, and the fuchsia-like flowers last a long time. They are usually pink, but modern hybrids include white, red, yellow and purple varieties.

The main difference between the Christmas, Thanksgiving and the Easter cactus is the time of bloom. The Thanksgiving cactus will usually bloom in late fall, one month before the Christmas cactus, whereas the Easter cactus starts producing flower buds in February.

I always wondered how my mother got her Christmas cactus to come into full bloom during the holiday season. She must have learned that the flower bud initiation on her cactus will respond to cool temperatures and shortened day length. Thanksgiving and Christmas cactus should be left outdoors, away from artificial light until night temperatures dip into the 40s. At this time, usually in September/October they should be brought into a cool room with temperatures between 50 and 65 degrees and be sure to keep them away from all light between the hours of 5 p.m. and 8 a.m.

Since the Thanksgiving and Christmas cacti are tropical plants they 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 Thanksgiving and Christmas cacti will require higher humidity and 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.

One rule is to never place the plants near a door that opens and closes to the outside. Likewise, keep it away from heating ducts or near the woodstove/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 your Thanksgiving/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 Thanksgiving/Christmas holiday season, the cacti should be given a 30-day rest period. Again, place them 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 Thanksgiving/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, these plants will flower best if it’s kept in a container where it’s a little pot-bound.

The Easter cactus is a little different in that it requires a dry period. From October to November, very little water is required for flower bud initiation. Easter cactus should also be placed in the same cool area under shorter periods of light at this time. In December, raise the temperature to about 65 degrees and water sparingly. With this regime you can expect flowering around March. The Easter cactus is a bit different since it is not a tropical plant and it requires a dry period.

That’s the story on not one but three holiday cactus. Seeing them bloom brings back many memories of the holiday seasons.

Bill Lamont is a professor emeritus in the department of plant science at Penn State and can be reached by email at wlamont@psu.edu.