Extension Notebook: Identifying and caring for holiday cacti

Poinsettias, amaryllis, holly and evergreens are common sites during the holidays. Another group of plants, holiday cacti, also make an appearance this time of year. With their brightly colored flowers ranging from white, pink, yellow, orange, red or purple, they are often given as gifts during the holidays.

While they are commonly referred to as Christmas cacti, there are several different types of holiday cacti sold: the Thanksgiving cactus, Christmas cactus, and Easter/Spring cactus. They get their common names from the holiday closest to their traditional bloom dates.

What holiday cacti do I have?

Most of the Christmas cacti sold are actually Thanksgiving cacti. To differentiate between the three types of holiday cacti, look at their “leaves” — the leaves are actually flattened stems. Thanksgiving cacti, also known as crab cacti, have pointed teeth along the outside margins of the leaves that look like hooks or claws. Christmas cacti have smooth, more rounded/scalloped margins. Easter cacti have rounded margins.

The flowers can also be used to differentiate the different types. Both Thanksgiving and Christmas cacti have tubular flowers. Easter cacti, on the other hand, have star-shaped flowers.

Caring for holiday cacti

While holiday cacti are true cacti, they are quite different from the cacti growing in deserts. Holiday cacti are native to tropical mountainous regions of southeast Brazil. They do not grow in the ground but are epiphytic, growing in the crotches of trees where debris and organic matter build up. Keeping this in mind, their cultural requirements are quite different from desert-growing cacti.

While plants are blooming, they should be placed in bright, indirect light with temperatures ranging from 70 degrees Fahrenheit during the day to 55-65 degrees at night. Soil should be kept moist. If plants get too dry while blooming, plants may drop their flowers. Once done flowering, they can be grown as houseplants.

During the summer, they can be placed outside in an area that receives light shade. Once temperatures start getting into the low 50s at night in the fall, they should be brought indoors.

Holiday cacti flower best when they are somewhat pot-bound, so they only need to be repotted every three years or so. They grow best in mixes that are well-drained and have good aeration.

Holiday cacti problems

One of the most common problems people have with holiday cacti is bud drop. This can happen for a variety of reasons, ranging from temperatures that are too high, exposure to drafts, insufficient lighting, under or overwatering, and low humidity.

Another common problem people encounter is the leaves (stems) of plants becoming wilted, shriveled/wrinkled, and dull-gray-green in color. This is most commonly caused by overwatering. Avoid excessive watering, and don’t let plants sit in water.

Getting holiday cacti to bloom

Holiday cacti are short-day plants, meaning they will begin blooming as nights get longer and days get shorter. To initiate blooming, plants need to have at least 12 hours of continuous darkness for five to six weeks. In addition to longer nights, plants need to be exposed to cooler temperatures. Keep plants in an area where daytime temperatures are 65-70 degrees and evening temperatures are 55-65 degrees. If they are kept in an area that is too warm, particularly at night, they may not bloom.

Ken Johnson is a University of Illinois Extension horticulture educator serving Calhoun, Cass, Greene, Morgan and Scott counties.