The Christmas cactus is a popular succulent that makes a great holiday gift because of the festive flowers it produces right around holiday time.
It is a low-maintenance plant that is easy to care for and grow, and does not need too much attention. This makes it a great choice for beginner gardeners who want a plant that is not too much of a responsibility.
One of the most serious problems a Christmas cactus owner can face is root rot.
Root rot is a condition caused by prolonged exposure of a plant’s roots to waterlogged soil, which obstructs their access to oxygen and causes them to drown and die.
The rot is a serious problem because it can spread to the stem and leaves of the plant and can eventually kill it, if left unchecked.
In this article, we will discuss the causes of root rot and what you can do to treat a Christmas cactus with this condition, as well as how to prevent it from happening again.
If you are experiencing this problem with your Christmas cactus and wish to learn more, just keep on reading.
What are the causes of root rot in a Christmas cactus?
Too much water
The most common cause of root rot in a Christmas cactus is overwatering. This can come about from giving the plant too much water every time you water it, watering it more often than you should, using soil or a pot that is poorly draining, leaving the plant out in the rain for several days, or not adjusting your watering schedule according to changes in the weather or the season.
Remember that the Christmas cactus is succulent, so it has the ability to absorb and store water in its body and leaves for use in times of drought. This is why Christmas cacti do not need to be watered as much as some other plants.
Overwatering, whatever the cause, makes the soil perpetually soggy and waterlogged. When the soil in the plant’s pot is always wet, the roots will be constantly standing in water rather than drying out completely between waterings.
Plants’ roots need to dry out completely between waterings so that they can have access to oxygen. If they are unable to absorb oxygen, they will drown and die.
The compromised roots will become susceptible to opportunistic pathogens in the soil, such as bacteria and fungi, and these will cause the rot to spread even faster to the rest of the plant. Soon, the stem and leaves will also begin to rot and the plant could quite possibly die.
Incorrect soil or pot
Another possible cause of root rot in your Christmas cactus is if you are using the wrong kind of soil for the plant.
The Christmas cactus likes a potting mix that is loose and well-draining. It does not take well to soil that is compact and dense, because such soil holds onto too much moisture.
You can check whether the soil is too dense by feeling it, or you can keep track of how long it takes for the soil to dry out completely after watering it.
The best type of soil for this plant is well-draining with a balanced pH level and should contain both organic and inorganic components.
Choose a potting mix that is the three-fourths substrate, one-fourth perlite, and has a low fertilizer content.
The pot that you use is just as important. Make sure it has sufficient drainage holes at the bottom, and that it is not too big for the plant.
If the pot is too big, you will need more soil to fill it. More soil in the pot means more water can be retained by the soil, hence the roots will be surrounded by moisture for longer.
If you are keeping the plant indoors on top of a saucer, make sure you empty the saucer after allowing excess water to drain into it when you water the plant. The water in the saucer can make the soil wetter for longer than the plant likes and thus can also cause overwatering.
Pests can also cause root rot in a Christmas cactus. This cause may not be as direct as overwatering or incorrect soil, but pests are capable of damaging the root system to the point that it cannot function properly.
If the roots are severely damaged, the cactus will no longer be able to absorb the nutrients that it needs.
One of the most common pests to attack Christmas cacti is the mealybug. These insects are so small that you might think they are dust particles on your plant.
If you think your plant has mealybugs, transfer it to another room where it is away from your other plants.
You can use a commercially available pesticide to kill these pests, but if you do not want to use chemicals in your home, there are other, safer home remedies.
You can use neem oil on the plant, for example. Mix two tablespoons of neem oil into water in a spray bottle and spray the solution directly on the affected areas of the plant.
You can also spray the plant with rubbing alcohol, or mix two tablespoons of mild dish soap to water in a spray bottle and spray that solution on the plant.
Repeat the treatment every three days until you are sure that no mealybugs are left on the plant.
How will I know if my Christmas cactus has root rot?
The first sign to watch out for is wilting. The leaves will look wilted, limp and wrinkled. When the plant’s foliage is in this state, it usually means the root rot is significant.
Another sign of root rot is if the leaves are falling off the plant. There are other reasons a plant’s leaves might fall off, but if the leaves and stems also feel soft and mushy to the touch, it is most likely due to root rot.
The most surefire way to know you are dealing with root rot is by removing the plant from the pot and inspecting the roots.
How to treat Christmas cactus root rot
If you suspect that the plant has root rot, gently take it out of its pot. The roots will be very fragile in this state and can be easily damaged.
Wash off as much soil from the roots as you can and inspect them closely. If there are any roots that have turned brown or black, those are rotten and will need to be pruned off. Use a sterile knife or scissors to remove the rotten sections until only healthy, white roots remain.
Spray the roots with fungicide and lay the plant on a dry paper towel to air-dry for several hours.
Prepare a new pot, making sure that it has drainage holes at the bottom, and fill it two-thirds of the way with fresh potting mix.
Since you have removed a significant proportion of the root system, the roots might have a difficult time supporting all of the foliage on the plant. To help it recover, prune off approximately the same proportion of leaves and branches as the roots you removed.
Place the plant in the middle of the new pot and cover the roots with the rest of the fresh potting mix.
Do not water the plant immediately; give it at least a week to recover from the trauma of repotting.
The best way to prevent root rot in the future is to water the plant correctly and always use a potting mix and pot that is well-draining.
There is no set schedule to follow when it comes to watering your Christmas cactus. The best and easiest way to know whether your plant needs water is to touch the top two inches of 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.
How to propagate a Christmas cactus
If your Christmas cactus happens to lose all of its roots due to rot, you can still salvage the plant by propagating it.
Collect some healthy-looking stem cuttings from the plant, place them in a warm, dry spot, and let the cuttings callus over.
The following day, place the cuttings in a container filled with potting mix. Make sure that one-quarter of the length of each cutting is below the surface of the soil.
Place the cuttings where they can get lots of bright, indirect light. Water them sparingly and just enough that the soil is always a little moist.
After three weeks, give the cuttings a little tug; if you can feel resistance, that means the roots are growing in nicely.
Wait a few more weeks before replanting the rooted cuttings in their own pots. Soon, you can start caring for each cutting in the same way you would a regular plant.
The Christmas cactus is a popular holiday succulent because it produces festive flowers just in time for Christmas. It is a low-maintenance plant that is very easy to care for, but it is not entirely immune to problems.
One of the most common and most serious problems a Christmas cactus can suffer is root rot.
Root rot is a condition caused by overwatering, incorrect soil, or pests. Once the roots of the plant have started to rot, the rot can spread to the rest of the plant and can even kill it.
You can save your afflicted Christmas cactus by removing the rotten roots and replanting it in a new pot with fresh potting mix.
If you lose all of the plant’s roots to root rot, you can always propagate it using any remaining healthy stem cuttings.
Avoid root rot by knowing how to properly water your plant and by using a potting mix and pot that are well-draining.
Image: istockphoto.com / L_Shtandel