Christmas Cactus is one of the three-holiday cacti, so named because each blooms around a specific holiday.
With its segmented, round-toothed stems called cladodes, hanging flowers, and distinctive pink pollen, the Christmas Cactus is a popular choice among succulent enthusiasts.
However, while generally low-maintenance, this plant isn’t immune to a few problems.
One of the most common of these problems is yellowing stems.
Why Is My Christmas Cactus Turning Yellow?
Yellowing Christmas cacti can generally be traced to two major causes:
- Improper care
- Infestation or infection.
Diagnosing the precise problem is a matter of elimination in some cases, but usually addressing the problem will allow your cactus to recover fully.
Too Much Or Little Light
Christmas cacti come from a genus of plants that grows in wooded areas, so it’s adapted for dappled sunlight.
Bright, indirect sunlight can be good for the plant as well, but you should avoid direct sunlight.
A large amount of direct light can bleach out the plant, making it appear yellow.
In time, the cladodes can even turn purple, which is a sign the plant is in severe distress.
To identify this problem, you simply have to check the plant several times during the course of a day to see if it’s being hit by direct sunlight at some point.
Solving the problem is equally easy, as you can simply move the plant or place something – such as a sheer curtain or a larger plant- in between it and the sun.
In a few days, you’ll start to see the green color returning.
The opposite is also true, as your cactus will become pale and take on a sickly yellow hue if it’s not getting enough light.
Again, this is easily diagnosed by observing the plant at various times of day to determine if it’s getting enough light.
If your cactus is getting less than 6 to 8 hours of bright, indirect, or dappled sunlight, you will need to shift it to a somewhat sunnier spot.
Infestations And Infections
Pests and disease tend to go hand-in-hand, as many common piercing bugs are vectors for the oft incurable disease.
The common pests of Christmas cactus include:
- Aphids
- Fungus gnats
- Mealybugs
- Scale
- Spider mites
- Thrips
- Whiteflies
Their feeding habits can cause yellow spots along the cladodes where they’ve sucked out the sap.
A neem soil soak will deal with all of them and may be used as a preventative.
Impatiens Necrotic Spot Virus is an incurable disease spread by thrips that causes yellow, brown-ringed spots.
Fungal infections are also a common problem caused by an infestation.
Some of these are dangerous, but most are easily treated through neem soil soaks, neem foliar sprays, and fungicides.
Malnutrition
All plants need at least some nutrients, and while epiphytes get a lot of their food from the air, they still require fertilizer.
Ideally, you should give the plant a monthly dose of balanced liquid houseplant fertilizer from spring through mid-fall, stopping for the end of autumn and winter.
You should also repot the plant every 2 to 3 years, giving it fresh, organically rich soil when you do.
Finally, Christmas cacti need a lot of magnesium.
Simply add 1 teaspoon of Epsom salts per gallon of water and give it to your plant during its watering time.
When possible, this feeding should be done midway between fertilizer feedings and should never be done at the same time.
Watering Issues
Plants don’t actually drink most of the water you give them.
Instead, almost all of the water is turned into a sweat in a process called transpiration.
This increases the local humidity around the plant, which prevents it from drying out.
When your Christmas cactus isn’t getting enough water, the cladodes will begin to flatten and fade to yellow.
It will also turn yellow with too much water, only the cladodes may appear swollen or mushy.
In both cases, the solution and diagnosis are part of a watering technique called soak-and-dry.
Here are the steps to do the method properly:
- Stick your finger in the soil and only water when it’s dry 2” to 3” inches deep.
- Pour the water slowly and evenly, moving around the pot, so the soil becomes evenly moist, and stop when you see water beginning to seep from the drainage holes.
In the event the potting mix is drying out quickly, it may be a matter of too much sunlight.
Conversely, slow drainage may mean you need to add some perlite into the soil.
A musty smell coming from the soil is a good indicator that the ongoing issue is root rot.
Dealing With Root Rot On A Christmas Cactus Plant
One of the most dreaded problems, root rot- usually from overwatering – can kill a plant if not dealt with quickly.
If you suspect root rot is the culprit, you will want to do a full soil change.
While the cactus is uprooted, check the root system for blackened or smelly roots.
Cut these away with a sharp, sterile knife.
You may also wish to add some perlite into the fresh soil to help prevent another outbreak of rot.