Spreading cheer

Holiday cactus splashes colorful blooms during Christmas or Thanksgiving

The holiday cactus can be persuaded easily to bloom more than once a year. If it blooms in November, it’s a Thanksgiving cactus; if it blooms in December, we call it a Christmas cactus.
The holiday cactus can be persuaded easily to bloom more than once a year. If it blooms in November, it’s a Thanksgiving cactus; if it blooms in December, we call it a Christmas cactus.

The red poinsettia is a star among the plants of Christmas, but for blooms that can come back year after year, consider the holiday cactus.

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Special to the Democrat-Gazette

The holiday cactus comes in a range of colors including salmon pink.

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Special to the Democrat-Gazette

Not to be confused with the difficult Christmas cactus Schlumbergera x buckleyi, the popular holiday cactus is Schlumbergera truncata.

photo

Special to the Democrat-Gazette

Holiday cactus blossoms are showy; this pink one is larger than most.

The word cactus conjures up visions of deserts and spines, not festivity, but the holiday cactus is spineless and puts on very showy blooms. Holiday cactus plants come in a wide range of colors and rebloom annually.

The holiday cactus is in the Schlumbergera family, a small family of cactuses with only six species.

Schlumbergera truncata (synonymous with zygocactus) is the one sold in stores as the holiday cactus. It is also called crab or claw cactus because of the crablike appendages on the flat, leaflike segments.

If S. truncata is in bloom in November, we call it a Thanksgiving cactus. If it is in bloom in December, we call it a Christmas cactus.

But there is another plant named "Christmas cactus," Schlumbergera x buckleyi. It has rounded leaf margins. It can be a bit more difficult to get to bloom, so it is not a popular plant.

And so the actual Christmas cactus is not, actually, the plant known and loved as our Christmas cactus.

FORGET THE SAND

Schlumbergera are true cactuses native to Brazil. This family of cactuses are not found in sandy, dry deserts. Rather they are epiphytic plants found growing in the rain forest.

Epiphytes are plants that root and perch on other plants or nonliving objects without being parasites. Instead they take moisture and nutrients from the air and rain. Schlumbergera share space with orchids and bromeliads.

Instead of barrel-shaped lobes with deadly thorns, these cactuses have wide, flat, segmented and succulent-leaflike branches and produce colorful, many-petaled flowers. The flowers come in a wide variety of colors: red, purple, peach, orange, pink and cream.

Most holiday cactuses now for sale are hybrids that can bloom over an extended period of time.

COLD BEFORE BLOOMS

The holiday cactus is thermo-photo-periodic in its flowering requirements. That means the plant is affected by day length and temperature.

The secret to good blooms is to maintain proper temperature and light control, but the temperature is more important. Holiday cactus will develop buds and bloom if given bright light, short days (of less than 12 hours of light per day) and night temperatures lower than 70 degrees (preferably between 55 and 65 degrees). After exposure to lower temperatures and short days for six weeks, flower buds are produced.

If they are left outdoors in the fall, they get the shorter days and lower temperatures

naturally and set a copious amount of flower buds.

If the temperature is lower than 55 (but not below freezing), plants set flower buds regardless of the length of the day or night. This can explain the phenomenon of reblooming in February and March.

These plants should never be exposed to freezing temperatures.

If you treat your plant as a houseplant year-round and keep your house at 70 degrees or above, you will probably never see a bloom. The plant needs the cool period to set buds.

NOT TOO LITTLE, NOT TOO MUCH

One of the recommendations you will often hear about encouraging a cactus to rebloom is to give it a dry period in the fall. A number of researchers have looked at this practice and found quite the opposite to be true: It will actually decrease bloom numbers.

Unlike most cactus, the holiday type doesn't like to get bone dry but it also won't tolerate heavy, water-logged soil. Water thoroughly, but allow the soil to become moderately dry between watering. Excess moisture results in root rot, especially during flower bud development in the fall when the plant is not producing a lot of new foliage.

The holiday cactus grows best in a lightweight, well-drained potting soil. The plant blooms best when slightly pot-bound.

Repotting is necessary only about once every two to three years. When repotting, gradually increase pot size.

As the blooms develop, give the plant a bright, sunny window. Avoid exposing the plant to drafts or extremely high temperatures. Flower buds can drop off if the temperature is too high or humidity is too low.

After the plant finishes blooming, place it in a room where it can receive some direct light. Poor light promotes bud drop and poor growth after flowering.

Full sun is beneficial in midwinter indoors, but full sun during summer months can make plants look pale and yellow. These plants grow naturally outdoors shaded by a canopy of leaves.

BLOOM AGAIN

If you have older plants that haven't bloomed yet this year and have no sign of flower buds, or your cactus has already finished blooming and you would like more flowers, move the plant to a very cool room of your house with bright light, or place the cactus near a cool window. Even a sun porch or garage with a window may work -- as long as they don't freeze.

If the plant receives six weeks with temperatures between 55 and 65, you should see it bloom.

In the summer, move the plant outside where it will get full morning sun and a bit of afternoon shade, especially during the hottest months of the summer. Most of the growing is done between April and September. Keep the plants evenly moist and fertilize monthly during this time.

Holiday cactuses are easy to propagate. In the spring or summer, take a cutting. The cutting should include two or three segments. Let the cutting dry for a few days, allowing a callus to form.

Poke the cutting into damp sand, deep enough to remain upright. Roots should form in about four to six weeks; at this point, pot the cactus in potting mix. Give it a relatively small pot to begin with, and gradually increase pot size over time.

Holiday cactus plants are relatively disease- and insect-free. Recent developments of vigorous new hybrids, offering a wide range of flower colors, have increased their popularity and availability. They are a welcome gift to give and receive and, with just a bit of care, can keep giving year after year.

Janet B. Carson is a horticulture specialist for the University of Arkansas Cooperative Extension Service.

HomeStyle on 12/20/2014

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