Backyard Gardening

By Kathryn Dorman

It’s amazing how much I learn when I research these articles. For example, I never knew that, along with the Christmas cactus there is also a Thanksgiving cactus and even an Easter cactus. As a group, these flowering houseplants are called holiday cacti. Their common names are derived from the holiday times around which they will naturally bloom.

Holiday cacti are all cactus (Cactaceae) family members, even though they lack sharp spines. Like most other cacti, holiday cacti also lack true leaves.  All photosynthesis takes place in the stems.  All three types of holiday cacti are native to the high-altitude tropical rain forests in the mountains of southern Brazil. They grow in decaying leaf litter which has been trapped among tree branches or rock crevasses. 

Holiday cacti are succulent plants with flat, fleshy, green, leafless branching stems. Plants can grow up to 12 inches tall and 24 inches wide. The pendulous growth habit of holiday cacti makes them a good choice for hanging planters. There are over 200 cultivated varieties (cultivars) of these plants, with flowers available in shades of orange, pink, purple, red, salmon, white, and yellow. 

Cacti in the Schlumbergera genus are often confused with Rhipsalidopsis, and species have been moved back and forth between the two genera. The Easter cactus is now called Rhipsalidopsis gaertneri. The species may be listed under several different names (NCSUE). Flowers of Easter cacti are radially symmetrical, relatively flat, and star shaped. Ironically, I think they look somewhat like the bracts of poinsettias.  

According to Clemson University Extension (CUE), it is possible for holiday cacti to live for 100 years. These plants require high humidity, bright but filtered light (as found in shady areas), and relatively moist soils for most of the year. It is critical that these plants be grown in well-drained soil and containers. Root rot (loss of roots due to overly wet soil) is one of the most common reasons these plants die. Set the plant over a shallow bed of clean pebbles to maintain high humidity but still prevent wet feet. Cover the pebbles with water, but do not allow the pot to sit in standing water.

In early June, remove (pinch back) the terminal stems.  This will promote branching, creating more terminal stems for the development of more flower buds. At the end of September, remove the shorter terminal stems. These immature stems will not produce flower buds. 

In the fall, Thanksgiving and Christmas cacti need shorter day lengths and cooler temperatures to produce flower buds. From mid-September until mid-November, “the secret to good flower production is bright but indirect light, night temperatures between 55° and 65° F, and uninterrupted nights of at least 13 hours of complete and total darkness. Buds may drop due to sudden changes in temperature, light, or lack of water (NCSUE).” Keep the plants out of drafty areas. The Easter cactus needs even longer periods of dark and cold for its flowers to form.  

Once new growth starts in late winter or early spring, water with a half-strength fertilizer solution once a month until the end of summer. Holiday cacti require more magnesium than many other plant species. During the growing season, but not the same week as when fertilizer is applied, water monthly with a solution of Epsom salts (magnesium sulfate) mixed at a rate of 1 teaspoon per gallon of water (CUE). 

Holiday cacti are non-toxic and can be grown in homes with pets and/or small children. Potential insect problems include aphids, mealybugs, scale, and spider mites (NCSUE).

I have searched in local stores and have yet to find a true Christmas cactus. Whether they are labeled as just “holiday” cacti or mislabeled as “Christmas” cacti, all I have been able to find thus far are the Thanksgiving cacti, with the notched stems. Luckily for me, a friend sent me a picture of a true Christmas cactus!  The flowers are very similar, and any holiday cactus can send a bright and flowery message of cheer at this time of the year!   

Kathryn Dorman has been a certified Penn State Extension Master Gardener of Clinton County since 2017. She can be reached at clintonmg@psu.edu or through the Master Gardener Hotline in Clinton County at (570) 858-0198.