Christmas Cactus

Christmas cactus is a popular plant. They are one of the three plants that make up the holiday cacti. Thanksgiving cactus and Easter cactus are the other two. Each of these species typically blooms around the date of their respective holiday. Christmas cactus is a tropical plant, so they take a little extra care to be able to bloom at the right time. Let’s talk about Christmas cactus and how to take care of them.
Even though we call it a cactus, the Christmas cactus doesn’t like dry and hot conditions. They are native to the tropical rainforests of Brazil. That means that you need to water them more regularly than a true cactus or other succulents. Once the plant has set flower buds, you want to keep the soil evenly moist to keep the buds from falling off. Don’t overwater and waterlog the soil. During the spring and summer, you can let it run a bit drier.
During the warm months, you can leave Christmas cacti outside, so long as they are out of direct sunlight. Direct sunlight will burn them up. If you leave them outside, you need to be wary of a frost because freezing temperatures will kill them. Generally, if temperatures go below 50 they need to be brought inside. Too much direct sunlight can damage them inside too.
To fertilize them, begin when new growth starts. Usually, this is either late winter or early spring. Fertilize with a balanced liquid fertilizer such as 20-20-20. If you use liquid 20-20-20 dilute it to half strength. Fertilize once a month throughout the month. Christmas cacti need extra magnesium as well. So fertilize with Epsom salts once a month, but not the same week that you put out the general fertilizer. Fertilizer contains salts, if the concentration of salts is too high in the soil, the water will become unavailable to the plant. Mix the Epsom salts at 1 teaspoon per gallon of water. Stop all fertilizing in the late summer for better flower bud production in the fall.
Sometimes people are disappointed when their Christmas cactus doesn’t bloom around Christmas. The trick is that Christmas cacti are photosensitive, like many other plants. Photosensitive means that they will put on flower buds in response to changes in day length. Christmas cacti need at least 14 hours of continuous darkness in the fall to set buds. These long nights should start in September and continue for 6 weeks to complete the bud set. The darkness needs to be continuous. If the darkness is broken for 2 hours bud set will be inhibited.
You can prune them in the late spring to encourage more branching and flowers. Simply cut off a few pieces of stem. Those pieces of stem can be placed in potting soil and kept lightly moist. After a few weeks, they will root and you have a new plant.
If you have questions about the Christmas cactus contact your County Extension Office or email me at Jacob.Williams@uga.edu.