How do I make my Christmas cactus bloom for Christmas?

ASK THE HORT AGENT

Question How do I make my Christmas cactus bloom for Christmas?

Answer Christmas, Thanksgiving and Easter cacti are three distinct plants (cacti is the plural of cactus). The first two are members of the genus Schlumbergera while the Easter cactus is in the genus Rhipsalidopsis. Both genera are native to Brazil.

The true "Christmas Cactus" is Schlumbergera x buckleyi, a hybrid between S. russelliana and S. truncata produced in the late 1840s by William Buckley at the Rollisson Nurseries in England.

Schlumbergera truncata cultivars are often sold as “Christmas Cacti,” yet they are really a “Thanksgiving Cactus.” They usually bloom before the true Christmas cactus which makes them a better candidate for Christmas sales. However, their flowers may not last until Christmas.

Both Thanksgiving and Christmas cacti bloom twice each year, in early winter and again in early spring. Therefore, people sometimes confuse them with the “Easter Cactus.” The Easter cactus, Rhipsalidopsis gaertneri, is similar to Schlumbergera. However, it blooms only once each year, in April (around Easter). Although its blooms are spectacular, they are infrequently seen because the true Easter cactus is a more finicky plant.

This information may seem confusing, but it may explain why your “Christmas Cactus” doesn’t bloom during Christmas.

Temperature and day length are the crucial bloom triggers for a Christmas, Thanksgiving or Easter cactus. Flower buds will form if one of the following conditions is met for approximately 8 weeks prior to your target date:

· night temperature maintained at 50 to 55 degrees Fahrenheit (the plant will produce buds regardless of day length)

or

· 13 hours of uninterrupted darkness per day (if the temperature is between 55 and 70 degrees)

Uninterrupted darkness means no light. Cover the cactus with a cloth or place it in a closet. When buds appear, increase the number of times you water but not the volume of water. Too much water and/or moving the plant may cause buds to drop off.

For more info on Christmas cactus care, visit http://www.sdnhm.org/research/botany/hp-cactus.html or http://hgic.clemson.edu/factsheets/HGIC1554.htm If you don’t have internet access then call me at 910-893-7533 or email me at gpierce@harnett.org

Christmas, Thanksgiving and Easter cacti are sometimes collectively called “Holiday Cacti.” They can also be called “Jungle Cacti” or “Forest Cacti.” The one at my house blooms whenever I least expect it. This plant takes me seriously as I often say “every day is a holiday.”

Gary L. Pierce

Horticulture Extension Agent

Harnett County