Christmas cactus: the other holiday plant

December 15, 2014 Updated: December 15, 2014 4:15pm

Q: Someone told me to water my Christmas cactus from the bottom only. Is this correct? I have a lovely one and do not want to kill it.

Perky Savage, Houston

A: I don't think it's necessary to water from the bottom only. The most important thing is to not over-water. Christmas cactus likes a damp or moist soil, but root rot develops in saturated conditions.

Use a well-draining, porous, organic soil such as a commercial cactus mix. Plastic and glazed containers hold moisture longer than terra-cotta pots.

Poke your finger into the top of the soil 1 to 2 inches. If it's dry, water. Allow the container to drain; empty any standing water in the pot saucer.

Christmas cactus is a sprawling epiphyte native to Brazilian rain forests with flat, gray-green stem segments (phylloclades) most of the year until it produces 3-inch tubular blooms in pink, peach, red, purple, fuchsia or white.




Schlumbegera bridgesii (named for Frederic Schlumberger, a 19th-century French cactus enthusiast) does not require pampering and can be long-lived. To enjoy indoors during the holidays, place the plant in bright, indirect light and away from vents and fireplaces.

After the holidays, apply a balanced fertilizer monthly or as needed during the growing season. Flush the soil occasionally to prevent salt buildup. Stop fertilizing in September.

Prune after blooms; remove one or two of the flattened segments to encourage branching and future blooms.

Many gardeners move their plants to a bright spot outdoors after danger of frost. Gentle winter sun is OK, but avoid summer rays, which will burn the foliage. Plants will survive temperatures from as low as 35 degrees up to 100 degrees, but growth is best in the 65- to 85-degree range.

Christmas cactus blooms are triggered by the length of daylight and cool temperatures. The plant sets buds when the days shorten to less than 12 hours and night temperatures are in the 50- to 60-degree range. Small buds appear on the plant in two or three weeks after being exposed to short days. Full bloom occurs in about two months.

It's possible an outdoor potted plant will get what it needs to set blooms: bright daylight, 13 to 14 hours of total darkness without the interference of street or porch lights and cool temperatures. Bring it indoors if the forecast is below 45-50 degrees.

Indoor plants need the same conditions to set blooms. To ensure total darkness, cover the plant with a box 13 to 14 hours each day beginning in October until color appears.

Keep in mind that bud drop can be triggered by temperatures above 90 degrees, sudden temperature changes, prolonged dry soil, poor light after buds set and ethylene gas produced by a heater or fireplace with poor ventilation.

Plants that are slightly pot-bound reportedly fare best, so repot only every three years or so.

Kathy Huber

Kathy Huber

Garden Editor, Houston Chronicle