By A. J. Senchack, Williamson County Master Gardener

Christmas cactus refers to many winter holiday plants whose common names are used interchangeably. Confusing?  Most gardeners who think they are growing a Christmas cactus are not actually growing a true Christmas cactus, Schlumbergera x buckleyi?  Ninety percent of what are sold at retail as a Christmas cactus are actually a Thanksgiving or false Christmas cactus cultivar, S. truncata var., and they are not even a cactus (an epiphytic succulent). These minor points aside (both plants look the same except for their “leaves”), we can still enjoy this month this tropical houseplant’s vibrant trumpet-shaped flowers, cascading down leaf-like stem segments. Bursting in a riot of flower colors—red, rose, white, cream, lavender, purple, peach, orange, and yellow—this “cactus” guarantees you can never have enough of them (see Figure 1).

So, what can we do to stimulate more cactus blooms next fall? The simple answer is grow it just like its wild Brazilian relatives—in a cool, shady, high humidity habitat in the crook of a tree. Not very descriptive of most homes’ indoors, is it?  Fortunately, Nature designed this succulent for containers and low maintenance. Let’s look at a few quick growing tips. First, use a loose, slightly acidic potting soil that mimics what its relatives enjoy so much, e.g., 3 parts leaf mold or bark chips, 2 parts sand, and 1part peat moss.  Commercial “cactus soil” is also good.  After blooming, give the plant a well-earned month’s rest and minimal watering to keep stems from drying out. Prune at this to make it bigger and bushier; then, propagate the cuttings for holiday gifts.  Next, when green shoots start to appear, begin watering thoroughly every 1-2 weeks or when the top third of soil is dry (do not overwater!).  Also, supplement your watering with a half-strength fertilizer (20-20-20) every 3-4 weeks until late summer.

Temperature and light determine success with Christmas cactus.  House temperatures suffice during its green growing phase (but 60°-65° is ideal). Give it bright, but diffused, light (direct sunlight may burn the leaves!) and increased humidity by placing it in a tray of pebbles or among other plants. During March-October, you can place your cacti outdoors in a partial to full shade porch area that gets early morning sunlight. Being a short-day plant, Christmas cactus begin initiating flower buds as early as October, but the critical variable is a 6-8 week period of cool darkness (>10-14 hours), either outdoors (bring in when temperature falls below 45°) or in a totally dark area of your home. Avoid exposing it to any temporary light, which disrupts the budding process.  Your cactus should reward you with a fully blooming plant by late fall that lasts up to 6-8 weeks, with individual flowers lasting 1-2 weeks. Keep the soil moist and stop fertilizing in bloom season. Frequent misting is a plus. And, don’t forget to share those cuttings with relatives and friends!