My Christmas cactus finally came into bloom – right on time, luckily, with no help from me.
One of the easiest garden arguments, other than the right folk name for Philadelphus (mock orange or English dogwood) and how to pronounce pecan, is over whether to call these holiday favorites Thanksgiving or Christmas cactus.
They are accidental holiday plants to begin with; in their native Brazil they are called Flor de Maio (May flower) because that is when they naturally flower. But when grown in the Northern hemisphere where days get shorter and cooler naturally in the fall, we assign them our holiday names.
Their leafless stems are actually flattened stem pads joined end-to-end, just like night blooming cereus, though some rare species have skinny, cylindrical stems like other another hanging succulent we call mistletoe cactus.
Their showy flowers are slightly irregular, with inner petals shorter than the outer ones; some have a “flower within a flower” look. Colors range from white to bright red, pink, deep purple, orange, salmon, yellow, and apricot; many have two-tone washes of a different color. My personal fav, a variegated beauty named Carnival, has pink-tinged green-and-white pads, with dazzling pink flowers streaked with white.
All these plants hang downward, because like Spanish moss and orchids they grow naturally from moss-covered tree branches or in rock crevices, often in small pockets of decayed leaves; this is why we grow them best in small pots without a lot of water.
Back to what to call these holiday beauties. Their subtle differences are interesting no matter what some folks insist on naming them. Easiest way to tell them apart is the earlier-blooming Thanksgiving species (Schlumbergera truncata), also called claw cactus has distinctive pointy “teeth” around the edges of its stem segments; the later-blooming hybrid Christmas cactus (S. buckleyi) has smooth, rounded lobes on their stem segments, and their flowers hang down more.
By the way, the barely related, much later-blooming Easter cactus with similar flattened stem pads, grows exactly the same way but its flowers are open and star-like, like zinnias, and the plants need a longer cool spell to set flower buds.
Being tree-dwellers, they don’t need to be grown in actual soil or big pots or lots of water and nutrients; keep them in small pots or hanging baskets in light shade outdoors in the summer or ideally an east window indoors, out of the AC or heater draft. Water only when nearly dry and fertilize very lightly only in spring and summer.
Big question with a lot of gardeners who keep these plants for years and share with small, rooted leaf pad cuttings is why some don’t bloom. It helps to recreate how they grow naturally, which happens accidentally for some gardeners like me.
Unlike the more familiar sun-loving desert cacti, they come from cool, shaded coastal mountains with high humidity, and flowering is triggered by a combination of lower temperatures and crucially just like with poinsettias, they require long nights to set flower buds.
Warm temps and regular watering can delay or prevent flowers. So, let them stay a bit drier in September or October, and, if you have bright lights in your house, cover them with a box or something during the day so they get 13 or more hours of darkness every night, for four or five weeks.
Once flower buds start to show, you can stop the long-night treatment and water a bit more. Keep in mind that the buds are a bit precocious -sudden changes can cause them to shed.
Great houseplants for a dreary season. No matter what you call them.
Felder Rushing is a Mississippi author, columnist, and host of the “Gestalt Gardener” on MPB Think Radio. Email gardening questions to rushingfelder@yahoo.com.
