Question: I was gifted a Christmas cactus for the holidays. Can you give me some advice on its care, maintenance, and especially, on how to make it re-bloom?
Answer: A healthy Christmas cactus in full bloom makes a great gift and holiday decoration. The Christmas cactus is different from many other holiday horticultural traditions in that it is literally the gift that keeps on giving.
Wreaths and trees dry up, poinsettias drop their colorful bracts, but there are Christmas cacti that are decades old, passed down from generation to generation. There have been stories of Christmas cacti living over 100 years. With proper care, the plants can bear hundreds of many-petaled, 3-inch long, tubed-shaped, rosy red or pink flowers at Christmas time.
Christmas cacti were developed from the species of Schlumbergera, a tree-dwelling cactus native to the tropical rainforests of Brazil. In the wild they grow propped up between tree branches and rock crevices, absorbing nutrients from rainwater and decaying leaves that get caught among their roots.
They are a type of plant known as “epiphytes,” a plant that grows on other plants, although they are not parasitic. Orchids, air plants and bromeliads are also epiphytes.
Many gardeners enjoy the challenge of keeping their Christmas cactus after the holidays for the next year. Despite their origins, Christmas cacti are fairly easy to care for and can be grown indoors throughout the year.
Many people think of cacti as being heat tolerant, but Christmas cacti will keep their blossoms longer in cooler temperatures. Keep your plant in a location away from drafts, heat vents, fireplaces or other sources of hot air. Drafts and temperature extremes can cause the flower buds to drop from the plant before they have a chance to open.
Christmas cacti are also not drought-tolerant. In fact, the plants will wilt under drought stress. The plants should be watered thoroughly when the top inch or so of the soil seems dry to the touch. The length of time between watering will vary with the air temperatures, amount of light, rate of growth and relative humidity. Be careful not to over-water your plant.
Over-watering can result in root rot and branches that can droop and break. Another consideration is adding fertilizer. The plant does not need to be fertilized while in bloom. Instead, while the plants are actively growing in the spring and summer, use a blooming houseplant-type fertilizer and follow the label directions for how much and how often to feed.
If your plant tends to dry out or wilt frequently, it may be time to repot the plant into a slightly larger container. For healthy, long-lived cacti, use a potting media that drains well and allows for good aeration. Peat moss, perlite and coco fibers are all potential media for potting.
Over time, say four to five years, the potting soil will break down and lose its aeration, and may actually become toxic to the plant roots. Invest in good potting media and pots that provide room for the cacti to grow for a few years.
Pruning your Christmas cactus in late spring or early summer will encourage the plant to branch out. Remove a few sections of each stem by pinching them off with your fingers or cutting with a sharp knife. These sections can be rooted in moist vermiculite to propagate new plants.
Christmas cactus can be moved outdoors in the summer but should be kept in a partial to completely shaded area. Direct sunlight can burn the leaves. During the summer, water your cactus to keep the growing mix moist after it dries on top.
When fall arrives in September, move the plant indoors after making sure no insects are tagging along. Spraying with a stream of water knocks off most insects that may try to hitch a ride. Place the Christmas cactus in a sunny location.
The most common problem encountered when growing holiday cactus is the failure to re-bloom. This is caused by a sudden change in temperature or moisture or exposure to light at the wrong time. Holiday cacti are short day plants; this means they will only form flower buds when exposed to over 12 hours of continuous darkness each night.
Any light that interrupts this continuous dark period can stop flower formation — even if it is from a street lamp or car headlights. Begin the dark treatments in about mid-October to have plants in full bloom by the holidays. You can place the plants in a dark closet from about 8 p.m. to 8 a.m. each night for 6-8 weeks or until you see buds forming.
Christmas cacti will also bloom if they are subjected to cool temperatures of about 50 to 55 degrees, eliminating the need for the dark treatments. Plants should be blooming for the holidays if the cool treatments are started by early November.
If you should receive a Christmas cactus as a holiday gift this year, by practicing proper care for this special plant, you can enjoy it for decades to come.