Three species of flowering cacti are sold as Christmas cacti. These include Schlumbergera bridgesii, Schlumbergera truncata and Schlumbergera gaertneri: the Christmas cactus, the Thanksgiving cactus and the Easter cactus.

The three closely related species are sold under their own names, or they may all be "lumped together" and sold as Christmas cacti or holiday cacti, depending on the store where you buy them. Learning how to recognize the differences between them is important, since they don't all naturally bloom at the same time.

Differences

All three species of holiday cacti look similar. However, the stem segments on a Christmas cactus are scalloped, while Thanksgiving cacti are toothed. Christmas cacti also have pointed, lobed leaves and produce carmine red flowers with purple centers at the tip of the stems.

Flowers bloom between December and February, while Thanksgiving cacti bloom from late October through November. Most Thanksgiving cacti produce scarlet flowers but other colors are available, including yellow, lavender, peach and white. Easter cacti closely resemble Christmas cacti but have wider leaves and rounded teeth on the stem segments. Pink and scarlet star-like flowers usually form in the spring.

Culture

Christmas cacti are usually grown as houseplants, but they can be grown outdoors in USDA hardiness zones 10 through 12. All three varieties of cacti require similar care. Grow plants in well-drained soil containing one part each potting soil and perlite and two parts peat moss or compost.

Provide light shade during the summer months and full sunlight in the middle of winter. Temperatures should be between 70 degrees F and 80 degrees F during the growing season. Avoid overwatering. Water the soil when it's dry to the touch and reduce watering over the winter. Fertilize monthly when new growth appears, but reduce fertilizer in the fall.

Problems

Flowering is the main problem Christmas cacti face. Underwatering, a sudden change in temperature or light, or the production of too many buds can cause them to drop their buds. Excessive light exposure will keep them from developing any buds at all. In addition, they are prone to root rot disease if they're overwatered. Insect pests include scales, spider mites, aphids and mealybugs.

Blooming

Flower buds form when temperatures drop and days grow shorter. Plants need cooler temperatures in order to produce flowers. Buds don't form if night temperatures exceed 70 degrees F, or if plants are exposed to artificial lights. There are several ways to encourage blossoming.

Reducing the night-time temperature to 50 degrees F or 55 degrees F will allow the formation of buds, even when your cacti are exposed to lights. If night temperatures are between 60 degrees F and 75 degrees F, you'll need to provide 12 to 14 hours of uninterrupted darkness between the months of September and November. You can do this by keeping the plants in a closet or inside a closed box. Flowers will grow at normal temperatures, once the buds are well developed.

How to Fertilize Your Christmas Cactus

The Christmas cactus is one of several holiday cacti. It earns its name from its habit of producing red or pink flowers during the winter holiday periods. The Christmas cactus belongs to a group of tropical cacti that require more water and fertilizers than those that grow in deserts. The plant primarily feeds in the period when it's not flowering. Supplying a regular flow of nutrients to the soil helps the cactus bloom at its fullest and keeps its succulent foliage healthy.

Dilute a 10-10-10 or similar complete fertilizer blend with water at half the rate recommended on the package. For most balanced houseplant fertilizers, combine 1/2 tsp. of fertilizer with 1 gallon of water.

Fertilize Christmas cactus after flowering. Continue to apply a soluble fertilizer every two to three weeks until late summer. Water the cactus with the fertilizer solution until the excess begins draining from the bottom of the cactus pot. Empty the drip tray under the pot after fertilizing.

Irrigate with clear water once a month, providing water until it drains freely from the pot. A clear water irrigation flushes any excess fertilizer salts from the soil so they don't damage the cactus plant.

Tips & Warnings

Mix the fertilizer in a clean gallon milk jug so you can easily store any that's left over after fertilization.

Overwatering can lead to root rot on the Christmas cactus. The soil only requires watering when the top inch feels dry, so the fertilizer watering may be the only irrigation necessary.