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Extension > Extension in your Community > Douglas > County Horticulture Educator > Articles > Why Does My Christmas Cactus Bloom at Thanksgiving?

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Why Does My Christmas Cactus Bloom at Thanksgiving?

Tis the season for holiday plants to start blooming. Many people may wonder why their Christmas cactus is blooming at Thanksgiving or even earlier.  There are actually several popular holiday cacti: the Thanksgiving, Christmas, and less familiar Easter cactus.  Despite the name cactus, these plants are not from the desert; instead, the Thanksgiving and Christmas cacti are both in the Schlumbergera family, and native to the tropical forests of Brazil.

Thanksgiving and Christmas cacti received their names because their typical bloom period is near the holiday; however, that is not always accurate.  Day length and temperature trigger bloom periods.  Therefore, your Thanksgiving cacti might bloom at Halloween and your Christmas cacti might bloom closer to Thanksgiving.  A more definitive way to tell the difference between a Thanksgiving cactus and a Christmas cactus is by looking at the leaves and flowers. The Thanksgiving cactus’ leaf segments have a pointed, jagged edge, while the Christmas cactus’ leaf segments are smooth and rounded. Upon closer inspection of the flower parts of the plan, the anther (pollen-bearing part of the flower) is yellow on the Thanksgiving cactus and purplish-brown on the Christmas cactus. Thanksgiving cacti are often sold as Christmas cacti, which only adds to the confusion.

To initiate flowering, either plant needs less than 12 hours of light per day and temperatures of less than 68°F.  Flower buds will set regardless of the daylight hours if temperatures are less than 55°F. If the conditions in your home do not meet these requirements, take these extra steps to trigger bloom.  Simply cover the cactus or put it in a dark closet for at least 12 hours a day. In some warm homes, if temperatures never drop below 70°F, the plant may never bloom regardless of the amount of light.

Warm rooms with low humidity can cause bud drop in budded plants. Plants that are overwatered may drop leaf segments. The perfect place for the cactus is in a bright, indirect light, with suitable temperatures away from drafts. Water the plant when the growing medium is dry to the touch. Do not overwater, especially in the winter. Keep the soil medium evenly moist in the fall when flower buds are set to prevent them from withering. Never let water stand in the saucer below the pot.  Fertilize the plant with a general-purpose fertilizer monthly during the growing season, fertilize with half strength from late winter through summer, and finally stop fertilizing in late summer for greater flower bud production.

When the cactus is no longer blooming, it will benefit from a “resting” period. Allow the soil to dry out between watering, but do not allow the leaves to shrivel. Thanksgiving and Christmas cactus bloom best when slightly pot-bound. The best time to repot is in spring when new growth begins. The best potting medium is well-drained soil with good aeration, such as a mix containing two-thirds potting soil and one-third perlite or course sand. Do not use a cactus soil mixture.

Take a close look at your holiday cactus: is it a true Christmas cactus, or is it a Thanksgiving cactus? Either way, with the proper care this plant will bloom for six to eight weeks each year for many, many years. For more information on all houseplants visit www.extension.umn.edu/garden/yard-garden/houseplants