The Christmas cactus is a beautiful succulent that is native to the rainforests of Brazil.
This plant is named for the fact that its flowers bloom right around the holiday season, making it a popular choice of holiday gift because of its festive look.
Although this plant is famous for its blooms, it is actually quite tricky to get it to bloom again the following year.
In fact, one of the biggest complaints among Christmas cactus owners is that their plant is not blooming.
The most common factors that impair blooming in a Christmas cactus are too much light, too much water, incorrect temperature, incorrect repotting time, incorrect container size, too much fertilizer, or the plant is not actually a Christmas cactus.
When does a Christmas cactus bloom?
The first thing you need to know is when this plant usually blooms. There is no point stressing over the plant not blooming if it is not even the correct blooming season to begin with!
The Christmas cactus blooms in late November or early December, just as its name appropriately suggests, and you can expect more flowers the more stems the plant has.
Why won’t my Christmas cactus bloom?
1. Too much light
One reason your Christmas cactus is not blooming may be that you are exposing it to too much light.
You might make this mistake because it is a cactus, but this is not a desert cactus and its lighting needs are quite different to those of its desert cousins.
When the plant grows on the ground in the rainforest, it only gets the dappled sunlight that penetrates the canopy of trees. If you place it in a spot where it gets too much direct sunlight, this can lead to sun damage and stunted growth. The leaves will also become wilted and may turn purple.
If you are keeping the plant indoors, you can place it next to a north-facing window during its non-blooming months, but to encourage blooming you will need to keep it in total darkness for 12 hours a day. Make sure that not even light from a lamp or a streetlight can reach the cactus, because even low light can break the cycle of darkness required to trigger blooming.
Start keeping the plant in a dark room for 12 hours a day during September or October. You might think this is too early, but you will need four weeks until buds appear on the plant and then another 12 weeks until they bloom. So, it is reasonable enough to start the process months ahead.
Once the buds appear, you can place the plant back at its north-facing window.
2. Too much water
Giving your Christmas cactus too much water can also hinder its ability to bloom.
The plant actually requires much less water before the blooming season than during the rest of the year.
Remember that this plant is succulent, which means it can store water in its leaves and stems for use in the event of a drought. It, therefore, does not need to be watered as much as other plants.
If the Christmas cactus is overwatered and its soil is soggy, this can attract bugs and pests that can damage the plant and discourage blooming.
Overwatering also leads to root rot, a condition caused by prolonged exposure of the roots to waterlogged soil. If the roots cannot dry out completely between waterings, they will not be able to absorb oxygen and will drown and die. The dead roots will be susceptible to opportunistic pathogens, such as fungi and bacteria, which will make the rot more aggressive and cause it to spread faster to the rest of the plant.
A Christmas cactus with root rot will have compromised root function and will be unable to absorb water and nutrients from the soil. This can even lead to the plant’s death.
If you suspect your Christmas cactus to have root rot, you need to remove it from its pot,
wash off as much soil as you can from the roots, and inspect them thoroughly.
If there are brown or black roots, those are rotten and will have to be removed. Use a sterile knife or scissors to prune off the rotten sections until only healthy, white roots remain.
Lay the plant on dry paper towels and allow the roots to dry out for a few hours.
Prepare a new pot that has drainage holes at the bottom and fill it two-thirds with well-draining succulent potting mix. Place the plant in the middle of the pot and cover the roots with more potting mix. Then, place the plant in a spot where it can get bright, indirect light.
You can prevent overwatering and root rot by adopting good watering habits. The easiest way to determine whether your plant needs to be watered is by touching the soil in the pot. If the top two inches of soil are dry, water the plant, but if the soil is still damp, wait one or two days before checking it again.
3. Wrong temperature
Another reason your Christmas cactus is not blooming could be that it is exposed to temperatures much higher than it requires to bloom.
This is a common mistake made by Christmas cactus owners because they assume the plant likes warm weather because it is a cactus.
While most cacti do love lots of direct sunlight and are used to living in hot climates, the Christmas cactus actually needs a considerable drop in temperature for blooming to start.
Just as you begin to deprive the plant of light in September or October to encourage blooming, you should also make sure that the dark place where you keep the plant is also much cooler than the plant’s usual spot.
The lower temperature will allow the flower buds to set in better. Keep the temperature at 55 degrees Fahrenheit; if it reaches upwards of 90 degrees Fahrenheit, the buds will fall off of the plant.
Do not expose the plant to freezing temperatures either. Keep in mind that it is a tropical plant that does not do well in cold climates.
4. Improper repotting time
If you repot your Christmas cactus at a bad time, this can also inhibit blooming.
These plants are fine with being slightly rootbound, so they do not need to be repotted every year. In fact, they typically only need to be repotted every three years.
The most obvious sign that the plant does need repotting is when you can see roots growing out of the drainage holes at the bottom of the pot.
The plant can go through several blooming cycles in the same pot, so do not worry about having to repot it after each blooming season.
The best time to repot a Christmas cactus is after the blooming season. Wait for the flowers to wilt and fall off before even considering repotting. Also, wait until the plant is at least three years old before repotting it for the first time.
5. The container is too big
As we already mentioned, this plant likes to be somewhat rootbound and will have no problem thriving in a smaller pot, even if the roots are somewhat restricted.
The plant actually prefers a certain level of stress in order to flower.
If you use a pot that is too big for the plant, it might use a lot of its resources and energy to grow more roots to fill the space, rather than using those resources to produce flowers.
If the plant is overly content and happy with its living conditions, it will find no need to produce flowers, because it feels no immediate threat to its survival.
When repotting your Christmas cactus, choose a pot that is only slightly larger than the plant’s root ball, so that it fits snugly. This will help promote blooming by causing just the right amount of stress to your plant.
6. Too much fertilizer
The Christmas cactus does not really need to be fertilized often because it is not a heavy feeder.
If you give the plant too much fertilizer, especially during September when you are supposed to be preparing it for the blooming season, this can prevent it from blooming and it will become quite droopy.
Use a half-strength liquid fertilizer that is made specifically for houseplants, and apply it once a month during the spring and summer. Stop feeding the plant at the end of summer so that it can prepare to form buds.
7. The plant is not a Christmas cactus
The most straightforward reason your plant is not blooming when it should is that the plant you have is not actually a Christmas cactus.
If you have ruled out all of the causes listed above and are doing all the right things to get the plant to bloom, and it still does not, then you might be taking care of a different plant entirely.
There are two other plants that look very similar to the Christmas cactus; these are the Thanksgiving cactus and the Easter cactus. The names of these plants also represent the time of year that they bloom.
Aside from that difference, they also have differently-shaped leaves. The Christmas cactus has scalloped or teardrop-shaped leaves, the Thanksgiving cactus has pointed projections on its leaves, while the Easter cactus has leaves with rounded edges.
The Christmas cactus is a popular houseplant that is often given as a holiday gift because of the time of year that it blooms.
Unfortunately, the plant may not bloom every year, and this can be due to one or multiple reasons.
The most probable reasons your Christmas cactus is not blooming are too much light, too much water, wrong temperature, incorrect repotting time, incorrect container size, too much fertilizer, or the plant is not actually a Christmas cactus.
The Christmas cactus actually likes to be under a certain, controlled level of stress to encourage blooming. Some of the steps to take to trigger bud production may seem a little weird, but this is what the plant needs in order to flower.
If you have ruled out all of the possible causes of a non-blooming Christmas cactus, then another possible reason for its lack of flowers is that the plant you currently have is actually not a Christmas cactus at all.
What you thought was a Christmas cactus may actually be a Thanksgiving cactus or an Easter cactus. In the eyes of a novice gardener, it may be tricky to try to differentiate between these three plants, because they look very similar. They differ only in the shapes of their leaves and the time of year that they bloom.
Image: istockphoto.com / Christine Wolf Gagne