Christmas cactus flowers may be yellow, salmon, pink, fuchsia or white, or combinations of those colors.
Christmas cacti (Schlumbergiera bridesii) are native to South American jungles, where they grow in decayed vegetable matter in the crotches of trees and on the limbs of trees, just as orchids and bromeliads do. It is not a parasite like mistletoe; it merely uses the tree for support.
Christmas cacti are long-lived: 25 and older is not unusual. They do best in a potting mix that's equal parts soil, sand and either peat moss or leaf mold. Many garden centers carry a potting mix designed for such succulents.
Christmas cactus is not a true cactus and is not as drought tolerant as the name infers. It is a succulent and stores a reasonable quantity of water in the leaves.
Water a Christmas cactus thoroughly when the top half of the soil in the pot feels dry, except during the summer, when you should water so the soil is continually moist.
In the fall, water the plant just enough to prevent wilting. This mimics its jungle habitat. It has two rest periods, before and after rainy times. One comes just before flowering in the fall. The other time follows flowering. Again, water sparingly.
These plants, like chrysanthemums and poinsettias, are short-day plants. This means that shortening of the day length triggers flower bud development. To get your plants to set flower buds, one of the following conditions must be met:
- Flower buds will form regardless of day length if the cacti are kept at 50-55 degrees temperature at night.
Christmas cactus will actually do best outdoors all spring, summer and fall. But even if you keep them indoors during spring and summer, take them outside in late summer, then bring them back indoors during late October or early November. Leaving them outdoors during the fall will provide the night temperatures needed for flower bud development.
- If the night temperature is 60-65 degrees, give the cacti 13 uninterrupted hours of darkness. You could place a cactus in an unused room or closet, or put a box over the plant.
After flower buds are well developed, they will flower at normal house temperatures.
After flowering, the plant will produce new growth, on which flower buds will appear the following year. During this period of active growth, provide more fertilizer and water. Fertilize at two to four week intervals.
About mid-August, you can reduce the watering to harden off the new growth. Withholding water slows down the plant's metabolism so that carbohydrates are stored with the plant rather than being used for new growth. From this time until flowering, the plant should be watered only sparingly.
While the Christmas cactus can adapt to low light, more blooms are produced on plants that have been exposed to high light intensity.
If your plants stay inside during the growing season, place them in a south or west window. Outside, they need to be in a shady or semi-shady location.
Christmas cactus grows best when pot bound, so plants rarely need repotting. If you do decide to re-pot, the best time is in the spring. A plant that is unhealthy because of the root system can be re-potted at any time.
A well-tended cactus can reach an unmanageable size. To limit the size and create more plants, root cuttings.
Take cuttings with three or four leaf sections whenever the plants are not in active growth. Allow them to dry for a day or two in airy shade, then place the cuttings in water, or in a peat and sand mix, or a peat and perlite mix. Water sparingly at first to prevent rotting. After two or three weeks, water as you would any other cutting.
When cuttings are rooted, pot them in a good, loose mixture or potting soil.
Sid Mullis is the director of the University of Georgia Extension Service Office for Richmond County. Contact him at (706) 821-2349 or firstname.lastname@example.org.