The Christmas Cactus is a plant with a long life, even if sometimes neglected. They brighten the winter with their cheerful blossoms and give plant lovers something to mull over: Is it a Christmas, Thanksgiving or Easter Cactus?
This family of cacti doesn't come from the hot desert. They come from the cool mountain rainforests in Brazil. They don't grow in soil but in pockets of humus-rich debris in the crotches of trees and cracks of rocks. They usually have a spreading, drooping habit.
Christmas cacti have been in cultivation a long time. The plants being sold today are clones of several crosses of two species, Schlumbergera bridgesii, or Schlumbergera russelliana, and Schlumbergera truncate that were developed in the 1800s. Typically they are given the names Thanksgiving Cactus or Christmas Cactus by the time of year they bloom. There are some slight differences in leaf shape in the different clones.
To add to the confusion, Christmas Cacti bloom can be manipulated fairly easily by growers, and the different varieties may be in bloom at the same time or even delayed until later in the spring, when they can be sold in place of the true Easter Cacti. Some varieties also bloom sporadically all winter.
The Easter Cactus belongs to another species entirely, Rhipsalidopsis gaertneri. It comes from the same general area as the other holiday cacti and requires just about the same care. It usually blooms in April.
The holiday cacti all have leaves that are thick and fleshy and occur in segments linked together. They are dark green. The base of the plant may turn woody as it ages. The earliest-blooming cacti have segments that have points at the top and a jagged side; the later-blooming cacti tend to have more rounded tops and smoother sides, although this is very variable. Easter Cacti have more rounded segments.
The Christmas/Thanksgiving Cacti produce buds at the end of a segmented stem. The buds take several weeks to grow from tiny bumps to long, beautiful flowers. Each flower is tubular, with satin-like petals folded back along the tube in layers. These varieties now come in traditional red along with pink, white, orange, yellow and lavender.
The Easter Cactus produces buds at the ends of stems and along the stem at other segments. The flowers of the Easter Cactus are rounder and more like a daisy than a tube. There are several shades of red, pink and mauve.
Growing holiday cacti
The rainforest cacti are grown by rooting one of the leaf segments. The leaf segments will root easily when stuck in damp vermiculite or gravel. Most gardeners will buy or be given potted plants, usually in bloom. Take the foil off the pot and place it in a bright, sunny window. Make sure the pot has drainage holes. There is no need to rush to re-pot the plant as most holiday cacti actually prefer to be rootbound.
Plants found in stores are usually only labeled by color, not by variety name. It is possible to find named varieties in catalogs and at better garden stores.
Your Christmas Cactus will bloom longer if your house is on the cool side, especially at night. Temperatures below 50 degrees or drafts may cause the plant to drop its buds. These plants need to be watered when the top of the soil feels dry, but don't over-water. Constantly wet soil will cause root rot. When not blooming, the cacti will survive longer without water, but if the stems feel limp and flat, you need to water.
To get your Christmas or other holiday plant to bloom again, it needs a summer vacation. After all danger of frost has passed, put it outside in its pot in a shady location in the South, partly or lightly shaded in the North. If the light is too bright the cacti will either turn reddish or bleach out. Make sure the plant will not sit in water when it rains. Bring the plant back in before frost.
The Thanksgiving or Christmas cacti need lengthening nights and cool temperatures at night to form buds. Keep the plant in a cool room with bright light and no drafts for best results. The trip outside will generally have allowed enough naturally shortening daylight to start buds forming. Easter Cacti begin blooming as the days start to get longer.
If you cannot put your plant outside for the summer, move it to a window where the sunlight is not too hot and strong in the summer. By late summer it should be getting cooler nights, about 55 degrees, and the same amount of light that is outside. You may want to cover it when it is dark outside or move it to a closet. Sometimes just the cooler nights will start buds forming. Once the buds have formed they usually continue to develop despite getting light at night.
When the cacti have buds, try not to move them to another location. This will sometimes result in dropped buds. Easter Cacti are a little harder to get to rebloom and a little more sensitive to drafts and improper watering, but they're worth the extra trouble.
In the early spring it doesn't hurt to give these cacti a little liquid houseplant fertilizer, just once and not too much. You can also pinch the plant back to promote more branching. The segments you pinch off can be rooted to start more plants. Stop pinching after June 1 or you will not have buds in the fall.
Christmas and other holiday cacti can live for decades; many people have plants 30 or more years old, passed from generation to generation. Every three or four years you may want to repot the plant. Use a mixture designed for cacti or mix peat, sand and vermiculite in equal amounts. These rainforest cacti like slightly acidic conditions. If you use hard, alkaline water to water them, you may want to add 1 teaspoon of vinegar to each gallon of water to increase the acidity.
If you care for it well, that small plant you got this Christmas may become a large, beautiful plant you pass to your grandchildren in 30 or 40 years.
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