Caring for Christmas Cactus
Christmas cactus is a long-lived tropical plant that flowers for about a month in winter. Not the drought-tolerant desert plant that its name suggests, Christmas cactus is native to Brazil, often rooting in collected leaves and other debris in the crotches of trees.
This popular houseplant doesn't tolerate having wet feet but it also doesn't want to be bone-dry. Use potting soil that offers excellent drainage, water when the top inch of the soil is dry and avoid over-watering; the plant is susceptible to root rot.
The hard part about raising Christmas cactus is getting it to keep its buds and to bloom. To set buds, the plant needs either nighttime temperatures between 50 and 55 degrees or about 12 hours of complete darkness every night. If you're doing the dark treatment, put it in a dark closet every evening. Car lights, security lights, even a television in the next room will interfere with bud set.
Bud dropping is common and can be triggered by too-dry soil, or some disruption in temperature or light pattern. To prolong the bloom period, keep the plant away from warm drafts.
After flowering has stopped, prune off a few sections of each stem to encourage branching. (You can root these sections to start new plants.) Fertilize lightly during the growing season. Christmas cactus does better when it's pot-bound, so re-pot only every few years.