Christmas Cactus

The Christmas cactus is a popular houseplant that bursts into bright flowers in winter. Unlike desert cacti, it is a jungle cactus from the cool, misty mountain forests of southeastern Brazil, where it grows on trees and rocks. Its flowers can be pink, red, purple, white, orange, or yellow.

Scientific Classification & Quick Facts

Common name	Christmas cactus
Scientific name	Schlumbergera
Kingdom	Plantae
Phylum	Tracheophyta
Class	Magnoliopsida
Order	Caryophyllales
Family	Cactaceae
Type	Tree-dwelling cactus with flat, jointed stems
Habitat	Shady, humid mountain forests; trees and rocks
Native range	Southeastern Brazil
Colours	Pink, white, orange, yellow, purple or red flowers
Special feature	Grows on trees, not in deserts

A Cactus That Lives in Trees

Christmas cacti belong to a small genus called Schlumbergera, which has six species. In the wild they grow in shady, humid places in the coastal mountains of southeastern Brazil.

Instead of growing in sandy soil, most of them grow on tree branches (they are epiphytes) or on rocks. They do not take anything from the trees; they just use them as a perch and get water and nutrients from rain, mist, and bits of decaying leaves.

The houseplants sold in stores are mostly hybrids and are known by several names, including Christmas cactus, Thanksgiving cactus, holiday cactus, and crab cactus, because of the claw-like shape of some stem segments. The Easter cactus looks similar but is a different, related plant that blooms in spring.

Two Main Groups

The Truncata Group (Thanksgiving Cactus)

These plants come mostly from Schlumbergera truncata. Their stem segments have sharp, pointed “teeth” along the edges, a bit like claws. Their flowers are held fairly level and are not symmetrical, with the top looking different from the bottom. Their pollen is yellow. They usually bloom earlier, around late autumn, so they are often sold as Thanksgiving or crab cacti.

The Buckleyi Group (Christmas Cactus)

These plants show traits of Schlumbergera russelliana. Their stem segments have rounded, scalloped edges, and their flowers hang down more and are more symmetrical. Their pollen is pink or purplish. They usually bloom a little later, closer to Christmas, and are the “true” Christmas cactus.

History

The French botanist Charles Lemaire named the genus Schlumbergera in 1858. He named it after Frederic Schlumberger, a plant lover who had a large collection of cacti at his estate near Rouen, France. Over the years, botanists placed these plants in several other groups, including Zygocactus and Epiphyllum, before settling on Schlumbergera.

What It Looks Like

Christmas cacti have no true leaves. Instead, their flat, green stem segments do the job of leaves, making food from sunlight. The segments are joined together in chains, so the plant has a branching, drooping shape that looks lovely in hanging baskets.

Flowers grow from the tips of the segments. Older plants can become woody at the base and grow quite large. In the wild, some species grow up to about 3 to 4 feet (1 to 1.2 m) across.

Why It Blooms in Winter

The Christmas cactus is a “short-day” plant. That means it forms flower buds when nights are long, usually at least 12 to 14 hours of darkness each night, and temperatures are cool, around 50 to 60°F (10 to 16°C). That is why it flowers in late autumn and winter. If your plant does not bloom, try keeping it somewhere cool where lights are not switched on at night for about six weeks in autumn.

Growing a Christmas Cactus at Home

Soil

Use a light, well-drained mix. A cactus or succulent mix with some ordinary potting soil or orchid bark added works well. Adding grit or clay granules keeps the soil airy so the roots do not stay soggy.

Propagation

Christmas cacti are easy to grow from cuttings. Twist or cut off a piece of stem with two or three segments, ideally a Y-shaped piece, from a healthy plant. Let it dry for a day, then push the bottom segment about a quarter of its length into slightly damp, sandy potting mix.

Keep the cutting in bright light, but out of direct sun. Roots usually form within a few weeks, and new growth shows that it has taken. You can then move it to its own pot.

Watering

How often to water depends on the pot size, the soil, and the temperature. From spring to autumn, water well when the top inch or so of soil feels dry, then empty any water left in the saucer, because standing water can rot the roots.

A handy trick is to lift the pot: dry soil makes the pot feel much lighter than wet soil.

Rest Period and Temperature

After flowering, the plant needs a rest. From late winter to early spring, water less often, just enough to keep the soil from drying out completely, and keep the plant in a cooler room at about 55 to 59°F (13 to 15°C).

From spring through summer the plant grows actively. Water more often and feed it every few weeks with a houseplant fertilizer. During this time, temperatures of about 65 to 70°F (18 to 21°C) are ideal.

Humidity

Because it comes from misty forests, the Christmas cactus likes humidity of about 50 to 60 percent. In dry homes, stand the pot on a tray filled with pebbles and some water, making sure the bottom of the pot sits above the water line.

Light

Bright, indirect light is best. Morning or evening sun is fine, but strong midday sun in summer can scorch the stems, so keep the plant a little back from a sunny window. In summer it can go outside in a sheltered, shady spot, away from heavy rain.

Pests and Diseases

Christmas cacti are usually quite tough. The main pests are mealybugs, including root mealybugs that feed underground, and aphids on new shoots and buds. Wipe them off or use an insecticidal soap.

The biggest problem is usually root and stem rot, caused by fungi and water molds such as Fusarium, Phytophthora, and Pythium. These are almost always caused by overwatering, so let the soil dry a little between waterings.

Good news for pet owners: the Christmas cactus is generally considered non-toxic to cats and dogs, though eating it may still upset their stomachs.

Christmas cactus FAQs

Related: May flower