Christian County Extension Office
The Christmas Cactus
Although it’s not as popular during the holidays as the poinsettia, the Christmas cactus has enjoyed a long history as a favorite winter blooming houseplant. Occasionally I hear of families who have a Christmas cactus which has been passed on from generation to generation. This is easy to believe as this plant is low on maintenance, tolerant of most growing conditions and lives a long life.
As a plant with such a rich history it is surprising that much confusion still surrounds the ‘holiday’ cacti sold during this season. First, you should note that there are three cacti sold as ‘holiday’ cacti. All three are similar in appearance and have similar cultural requirements.
One is the Thanksgiving cactus (Schlumbergera truncata). This cactus generally blooms from Thanksgiving through the Christmas season. They differ from the true Christmas cactus as their leaf margins bear 2 to 4 sawtooth points on the sides of their stems that point upward. They bloom in shades of red, lavender, and salmon-orange. Many people who believe they are growing a Christmas cactus may actually have a Thanksgiving cactus due to its availability at many outlets during this season. The true Christmas cactus blooms too late for good sales. The Easter cactus (Rhipsalidopsis gaertneri) is sometimes confused with the Christmas cactus because both have leaves with smooth ripples along the margin. However the Easter cactus blooms much later, generally March through May, with occasional re-bloom in the fall and its flowers are very different in form. The Christmas cactus (Schlumbergera bridgesii) blooms in shades of red, purple, orange, pink, and cream from late December through March. Its leaves do not have the points along the margin as the Thanksgiving cactus and has more distinct ripples than the Easter cactus. Its branches are decidedly arching and pendent, which makes it a great choice for hanging baskets.
As the Christmas cactus is tropical in nature, hailing from the rainforests of South America, it has very little in common with its desert cousins. This is especially true concerning water. Flower buds may drop and the plant may wilt if the soil gets too dry. Keep the soil evenly moist to the touch (not saturated) from spring through summer but allow the soil to dry out some between watering from fall through spring. How often you water will vary with the air temperature, sunlight, growth rate, and humidity. Your plant should be placed to receive full sun exposure during the winter and filtered light during the summer months. More blooms are produced on plants that have greater light but leaves may start to turn red and actually burn if sunlight is excessive, especially when grown outdoors during the summer. Ideal growth occurs when temperatures are between 70 to 80 degrees from April to September. Once flower buds are set keep the plant away from heat sources such as vents, fireplaces, or other sources of hot air as the increase temperatures may cause flower buds to drop. Fertilize Christmas cacti when new growth starts from the branch tips in late winter or early spring and monthly through summer using a one-quarter strength soluble fertilizer. Reduce fertilizer during the fall and early winter. After flowering, prune a few sections of each stem to encourage the plant to branch out.
Christmas cacti do not need to be repotted annually and actually prefer their roots to be a little cramped. Repotting should occur when the roots have outgrown their containers or whenever the plant is not setting buds or blooming. Use a commercially packaged potting mix for succulent plants or mix your own by combining two parts plain potting soil with one part clean sand or vermiculite.
Christmas cacti have few problems although mealybugs and scale can sometimes be problematic. The most common problem people report has to do with blooms – either lack of flowering or the flower buds drop off. To produce buds, Christmas cacti must have nighttime temperatures in the high 50’s to low 60’s. If you cannot provide cooler nighttime temperatures, place the plant in total darkness each night for about thirteen hours of uninterrupted darkness for six to eight weeks or until buds form. Long nights should be started about the middle of September in order to have blooms at Christmas. Bud drop is often associated with environmental changes once the buds have formed. Buds will abort if the plant is placed in a drafty location, excessive or dim lighting, or if being over-watered.
If you decide to give someone this celebrated holiday bloomer for Christmas be sure to select one with healthy foliage and bright, clear colored flowers. New flower buds are a plus. And remember that a Christmas cactus by any other name – could be a Thanksgiving or Easter cactus.