With their exotic-looking flowers adorning gracefully drooping stems, holiday cacti – both Thanksgiving and Christmas cacti – are favorite plants to give and receive. But once you take the colored foil off, how do you keep the plant healthy and happy for the New Year?
These spineless, succulent cacti are native to the Brazilian rainforest, which gives an indication of the kind of care they require. Unlike desert-dwelling cacti, these plants need to be kept moist, and they don’t need full sun. Bright, indirect light and evenly moist soil most closely replicate their natural environment, where they are typically found growing in pockets of leaf mold high in the trees. Mimic these conditions and your plants will have the best chance of thriving.
A plant in bloom will often drop some flowers when it’s brought into a new environment, often because of sudden temperature changes. To reduce this loss, keep plants away from heat sources such as hot air ducts and fireplaces. Ethylene gas from space heaters and gas stoves, as well as ripening fruit, can also cause bud drop.
Holiday cacti grow well in our typical 70-degree homes, and turning down the thermostat at night helps them, too. Give them an acidic soil with high organic matter content, such as a mixture of 60 percent peat moss and 40 percent perlite. To test the soil for moisture content, stick a toothpick into the soil and if it comes away clean, it’s time to water.
Once the plant has finished flowering, reduce watering but don’t let the leaves shrivel, and place it in a cooler location for the next several months. When new growth begins in spring, begin fertilizing at half strength and continue until fall. If possible, set the plant outside in the shade for the summer. If you leave the plant outside (temperature permitting), it will naturally begin blooming in late fall.
To encourage blooms at Christmas time, in mid October start giving the plant 14 to 16 hours of complete darkness at night. Move it into a closet, cover it with a box, or place it in a room that you don’t use at night. It will take at least three weeks of this treatment for the buds to show about 1/8-inch long, at which point you can stop the long-night treatment. In the absence of long nights, exposing the plant to temperatures of 50 to 55 degrees at night will initiate flower buds.
Holiday cacti flower best when kept somewhat root bound. Every three or four years, repot your plant by removing it from the pot, cutting off about one-third of the outer roots, and repotting it with fresh mix into the same size pot.