The Christmas cactus (Schlumbergera bridgesii) blooms for a long time indoors with some of the most exotic-looking flowers in the plant kingdom. This cactus is a very popular plant, but most people are not aware of its special needs. Not all cacti are native to arid desert climates and require infrequent, sparse watering. The Christmas cactus actually calls the tropical rain forest home, and thus needs watering when the top inch of soil in the container feels dry to the touch.
Soak the soil until water runs through the pot’s drainage holes; wait a few minutes; and then discard any excess water that has accumulated in the drip pan beneath the pot. A water-soluble fertilizer recommended for flowering houseplants can be applied during its active growth, but be sure to follow the directions on the fertilizer container regarding the amount and frequency of application.
Christmas Cactus Care
The Christmas cactus prefers humid conditions, and homes are often dry. One way to raise the humidity — just for your cactus — is to place the pot with its drip pan on top of a small container filled with pebbles. Pour water over the pebbles, but do not allow the water to rise above the bottom of the top layer of pebbles. The water will evaporate, increasing the humidity around the cactus.
Temperature and day length provide crucial bloom triggers for the Christmas cactus. The term for this response is "thermo-photoperiodic." Flower buds will form if one of the following conditions is met:
- a cool night temperature between 50 to 55 degrees
- 13 hours of uninterrupted darkness (if the temperature is between 55 and 70 degrees)
- 15 hours of darkness (if the temperature is above 70 degrees)
Uninterrupted darkness means NO light during the dark period, including lamp light within the home. Cover the cactus with a black cloth or plastic bag, or place it in a closet. Pay attention to the light schedule, and do not fertilize or overwater.
Plan for Bloom
When do you want blooms — for Christmas or Thanksgiving? Count backward eight weeks to determine the autumn date to begin to prepare the plant for reblooming. When buds appear, increase the number of times that you water, but not the volume of water used. Too much water may cause buds to fall, as will moving the pot around. The Christmas cactus will remain in flower for four to six weeks, with each flower lasting six to nine days. After the plant has flowered, prune back each stem by pinching off enough sections to achieve a uniform habit. Resume normal watering and fertilization when new growth appears.
Christmas cacti require direct sunlight, but take precautions against the burning midday summer sun: If you choose to leave your plant indoors during the warm months, move it a few feet away from the window to avoid burning the stems. If the plant is moved outdoors, it still needs protection when the sun is at its zenith.
The spectacular show of flowers will be well worth the effort!