Answer: Christmas cactus will bloom if given long uninterrupted dark periods, about 12 hours each night. Begin the dark treatments in about mid-October to have plants in full bloom by the holidays. You can place the plants in a dark closet from about 8 P.M. - 8 A.M. each night for 6-8 weeks or until you see buds forming. Christmas cacti will also bloom if they are subjected to cool temperatures of about 50 to 55 degrees F, eliminating the need for the dark treatments. Plants should be blooming for the holidays if cool treatments are started by early November.
We typically think of cacti as being heat tolerant, but Christmas cacti will keep their blossoms longer in cooler temperatures. Keep the plant in a well-lit location away from drafts from heat vents, fireplaces or other sources of hot air. Drafts and temperature extremes can cause the flower buds to drop from the plant before they have a chance to open.
Christmas cactus is a tropical type plant, not quite as drought tolerant as its desert relatives and, in fact, may drop flower buds if the soil gets too dry. The plants will wilt when under drought stress. Water thoroughly when the top inch or so of soil feels dry to the touch. The length of time between waterings will vary with the air temperature, amount of light, rate of growth and relative humidity.
I'm glad you like Monrovia plants! The Monrovia catalog of plants is available on the Monrovia website (sorry, no hard copies available). There is a page on the site where you can enter the growing conditions and your flower color preference and the possible plants will be found in the database and listed for you. If you find something you especially like you can print off a copy of the page. Happy hunting!
Q&A Library Searching Tips