Dear Miss Floribunda,
Every December I buy a beautiful Christmas cactus and by the next December it is history. I thought cacti thrived on neglect but no matter what I do, I can’t keep this kind alive. Last month you passed on some gardening advice that you got from your sister-in-law from Sonora. I believe Sonora is cactus country. Could you give me some more tips?
Cactus-Challenged on Hamilton Street
The first thing my Mexican sister-in-law Picante had to say after reading your letter was, “That Christmas cactus is not desert cactus but tropical cactus!” She explained that these zygo-cacti (Schlumbergera) behave like orchids: they are epiphytes that grow in trees in coastal mountain regions of Central America and Brazil where they are pollinated by hummingbirds. Picante breeds them by taking cuttings when she trims them in early spring and she says they can last for many years with proper care. The catch is that they need tropical — not desert — conditions to survive.
Because they grow in tight pockets in trees, they like to be pot-bound. It is a good idea to prune and re-pot them in new soil in early spring but don’t put them in larger pots until they’ve gotten so large that they are starting to wilt. Basket-like orchid pots are best for them, filled with light and acidic soil, such as that sold for succulents. Use a 20-20-20 fertilizer no more than three times per year and a 0-10-10 fertilizer in late October. During their blooming period, they should be watered lightly every other day or the flowers will fall off. When not in bloom, they should not be watered frequently (about once a week), but they do need a moist environment. You could keep a container of water next to your plants or place them on a humidity tray of gravel, only halfway filled with water. Of course, mist them regularly. Picante advises placing them in a north- or east-facing window, if not drafty, with sheer curtains to filter the sunlight. They like plenty of light but not harsh light. In their natural habitat, the tree canopy filters the light for them and protects them from being drenched by rain although moisture in the air is constant. Because they naturally grow at high altitudes, they like a cooler temperature at night, if manageable. They need shade, and if their leaves turn reddish that means they are getting too much sun.
To get them to bloom again by next Christmas, cut back on light in October and keep them from excessive heat or cold. A cool basement is a good place for them. If your basement is any warmer than 65 degrees Fahrenheit, you will need to keep your cacti in a dark place (like a closet) for twelve hours each day to get them to bloom again. Or, do as Picante does and just pop a box over them overnight. Fertilize with a low-nitrogen 0-10-10 fertilizer to encourage the development of flowers rather than green growth.
To discuss this and other horticultural questions and meet fellow gardeners, please come to the December meeting and party of the Hyattsville Horticultural Society on Saturday, Dec. 19, from 10 a.m. to noon. It will take place at the festive home of Jean and Millard Smith at 3600 Longfellow Street.