Extension Educator, Horticulture
Holiday cacti are known for their colorful tubular flowers and ease of care. They include Christmas, Thanksgiving and Easter cacti. Christmas cacti have flattened leaves with rounded teeth on the margins as opposed to the Thanksgiving cactus that has pointed teeth. Easter cacti have pointed teeth with fibrous hairs in the leaf joints. Under normal conditions the holiday cacti will bloom close to the holiday suggested in its name. Florists will often force plants into bloom at other times. To make things really confusing, most of the Christmas cactus sold are actually Thanksgiving cactus and will bloom in subsequent years at Thanksgiving time. So don't be surprised if the plant you bought this year blooms next Thanksgiving.
Of all the plants passed down from generation to generation, holiday cacti are mentioned the most often. I've had numerous calls from people who have inherited grandma's Christmas cactus. The pressure of keeping a family heirloom alive is obvious in their voices. My suggestion: Take lots of cuttings and give to relatives. It's always best to spread the pressure around.
Holiday cacti are actually quite easy to care for once you understand the basics. When the plants are in flower, they should be kept in bright, indirect light. Too much light can cause the flower color to fade or the heat my cause the flower buds to drop. Day temperatures of 70°F and evening temperatures of 60-65°F are considered ideal.
Be sure to water thoroughly, but let plant dry slightly between waterings. However, Christmas cactus are not as drought tolerant as the name suggests. It is especially important not to let them dry too much during flowering or they may drop the flower buds. The leaves will wrinkle if the soil is too dry. Leaves may also wrinkle if the plant has been overwatered. Check the stem and roots for rot.
Once flowers fade, continue to grow the plant as a houseplant. Soil should be well drained. Fertilize monthly between April and October with a complete houseplant fertilizer. Prune plants in June to encourage branching, even flowering time and more flowers. Just remove a few sections of each stem with your fingers or a sharp knife. The removed pieces can be rooted in moist vermiculite to make more plants.
Getting them into flower requires a little understanding of what makes them tick. Holiday cacti are short day plants meaning they bloom when nights are at least 15 hours long. Holiday cacti will also flower if exposed to prolonged cool temperatures between 50-55°F. No flowers will form at night temperatures above 70 °F. Holiday cacti can be placed in a shady spot in the garden in summer. I just leave mine outside or in an unheated porch. Once temperatures get below 45°F I bring it indoors. The naturally longer nights and cool temperatures in late summer will encourage flower development. People have told me they just virtually ignore them in a spare bedroom or garage where temperatures are cool and no lights are used at night. A little water once and awhile and they are rewarded one day with a plant full of blooms.
A common problem with Christmas cacti are dropping unopened flower buds, which may be caused by an excessive number of buds, a sudden change in temperature or light or dry soil. Lack of flowering is often due to light interrupting the required long night period or high temperatures. Streetlights, car lights or indoor lighting may disrupt the required dark period. The major disease is root rot, which can be prevented by avoiding excessive watering. The most common insect pests are mealybugs and soft brown scale.
Take care of your cactus and leave it in the will to the kids.