Gardening Know How gets many questions pertaining to all manner of plants and issues that pop up when cultivating them. One of these include the ever popular Christmas cactus. Below you will find the 10 most commonly asked questions about Christmas cactus that we receive when growing these houseplants.
Some Christmas cactus plants bloom on their own, but others need a little encouragement. To get a Christmas cactus to bloom, begin about eight weeks before you want the plant to bloom. During the night, place the Christmas cactus in a cool location where temperatures are consistently around 50 F. (10 C.) and the room is dark, with absolutely no artificial lights (including porch lights or street lights). Ideally, Christmas cactus is in the dark for at least 14 hours. Bring the cactus into a warm, bright room during the day. Resume normal care when buds appear.
It can be difficult to determine why buds fall off a Christmas cactus. A move to a new location with drier air or a significant change in light or temperature are among the most common reasons. Be sure the plant isn’t getting blasted by hot air or a cold draft. It’s also possible that your cactus isn’t getting sufficient light during the day, so it might pay to move it to a slightly sunnier spot. Christmas cactus plants need fertilizer during the growing season, but they do a better job at setting buds if you stop feeding the plant about mid-September.
Christmas cactus is a cinch to propagate. Just remove a stem with at least two or three segments. Set the stems aside for three or four days to allow the cut end to heal. Once the cut end has callused, plant the stem no more than 1 inch (2.5 cm.) deep in a small pot filled with moistened mixture of commercial potting soil and a little sand. Place the pot in bright, indirect light. Water sparingly whenever the surface of the soil feels dry, until new growth appears.
It’s fine to prune back Christmas cactus in late spring to encourage more branching or to neaten up an untidy or overgrown plant. Remove a few stems at the segment joints with your fingernails or a clean, sharp knife. Stand back and look at the plant to ensure branches look even on all sides, then trim a bit more, if necessary. Feed the plant lightly after pruning, using a water-soluble fertilizer. Don’t forget: You can always use the pruned segments to propagate new Christmas cactus plants.
To encourage blooming, feed Christmas cactus once in late October or early November, using a low-nitrogen fertilizer with a ratio such as 0-10-10. Never fertilize the plant after it begins to flower because doing so may cause buds or flowers to drop. Feed the cactus one more time in February, using the same low-nitrogen fertilizer. Switch to a monthly application of a balanced, water-soluble fertilizer every month during active growth, generally from April to October.
When Christmas cactus is unwilling to flower, it’s likely a matter of light and temperature. Christmas cactus plants need to be in darkness at least 14 hours per day for about six weeks prior to the time you want it to bloom. Move the plant into bright, indirect light during the day. Temperature during this time should be cool – 50 to 60 degrees F. (10-15 C.). The plant will never bloom if nighttime temps are above 68 F. (20 C.). The potting mix should be fairly dry during this time. Provide just enough moisture to keep the leaves from shriveling.
In its natural environment, Christmas cactus is an epiphytic plant that grows in the tropical rain forest. It’s absolutely fine to take your Christmas cactus outdoors in spring, but only if you’re sure nighttime temperatures are above 50 F. (10 C.). Put the plant in indirect sunlight and avoid intense sunlight, which can scorch the plant. If you live in a climate with hot summers, light shade may be beneficial, especially during the afternoon. Bring the Christmas cactus back indoors when nighttime temps drop to 50 F. (10 C.).
Christmas cactus is happiest when its roots are a bit on the crowded side, so don’t be in a hurry to repot. As a general rule, every three or four years is usually often enough. It’s time to repot your Christmas cactus if you see roots growing through the drainage hole, if water runs straight through the pot, or if growth is stunted. Repot the plant into a container only one size larger after flowers have wilted in late winter or early spring. Use a commercial mix formulated for cactus or a mixture of two-thirds regular potting mix and one-third sand.
There are several things to investigate when a Christmas cactus leaves are limp and flat, including inadequate watering. If you think this may be the case, water the plant lightly every few days and see if it begins to rebound. On the other hand, beware of overwatering; too much water may cause rot, which can also cause shriveling. If the plant is in intense sunlight, try moving it to a spot in indirect sunlight. Sometimes, very old plants decline no matter what you do. If this is the case, start a new plant from a few healthy stems.
Too much sun is often to blame when Christmas cactus leaves turn purple. The discoloration may affect the entire plant or only the side facing a too-bright window. As a general rule, Christmas cactus plants need bright, indirect light, not intense sunlight. It’s also possible that a nutrient deficiency may be causing Christmas cactus leaves to turn purple. Try feeding the plant a balanced, water-soluble fertilizer every month from spring until fall.
We all have questions now and then, whether long-time gardeners or those just starting out. So if you have a gardening question, get a gardening answer. We’re always here to help.