Your children know all about Christmas trees, but they probably don't know quite as much about the Christmas cactus (Schlumbergera truncata ). Although some bloom with bright-red flowers on green leaves -- the traditional colors of the holiday season -- the plant is named for the fact that it blooms around Christmastime. These plants feature other colored blooms as well, including white. Sometimes, white Christmas cacti have blooms that are tinged with pink.
The bloom color on a single Christmas cactus can vary from its original color because of environmental conditions or a genetic break, according to the North Dakota State University Extension Service. This means flowers that were previously white may develop pink tips, or turn entirely pink, purple, orange or another color. In addition, some white-flowered cultivars have pink stamens, pink edges or just a hint of a pink blush in their centers.
Christmas cactus plants are most often grown indoors. Although their common name implies that they are desert plants, Christmas cacti are actually native to the humid forests of Brazil. They are succulents, not cacti. Outdoors, the plants are hardy in U.S. Department of Agriculture plant hardiness zones 10 through 12.
Christmas cactus plants thrive in partial shade. Too much direct sunlight will bleach out their stems. In the winter, they can tolerate more sun. They like moist, well draining, light soils -- try a mixture of 2 parts cactus medium to 1 part potting soil. Too much water will cause their roots to rot, so err on the side of overly dry soil -- the plants can tolerate periods of drought better than wet conditions.
Christmas cacti are notorious for dropping their blooms before the flowers open. First, encourage bud development by placing your cactus in a cool, dark location for at least 13 hours a day starting in mid-September or October. You may be able to achieve this simply by leaving the plant outdoors when cooler fall temperatures arrive -- nighttime temperatures that hover around 55 degrees Fahrenheit are ideal, according to the University of Illinois Extension. Then, give it plenty of sunlight during the day, and be patient. By Christmas, your plant should be covered with pink and white blooms.