The colorful flowers and unique shape of Christmas cacti have earned them a spot in many homes across the globe.
Then there’s the fact that they’re tough and sturdy, hardly needing any care to thrive and flower.
But just because they’re tough, that doesn’t mean these succulents never have problems. One of the most obvious signs of trouble is leaf drop.
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Holiday cacti will drop their cladodes – the leaflike structures – naturally as they age. It’s usually just one or two here and there, and the plant will look perfectly healthy otherwise.
Speaking of, check out our guide to growing Christmas cactus to learn what it takes to keep your specimen in good shape.
But if young leaves are falling or more than a few are dropping at a time, you need to read this guide and figure out what’s going on.
Here’s the list of issues we’ll go over:
Reasons Why Christmas Cacti Drop Leaves
The first topic we’ll discuss is probably one of the least common unless you are a chronic overwaterer.
1. Disease
If the cladodes are falling and you notice little tan lesions or black water-soaked spots on the foliage, you’re probably dealing with Fusarium wilt, caused by the fungus Fusarium oxysporum.
This pathogen needs a lot of moisture to thrive and spread, so overwatering or keeping your plant in poorly draining soil or containers can invite it.
You might be able to save the specimen if you catch it early enough, but if not, your best bet is to take a cutting to propagate a new plant and toss the infected one.
To determine if you can save your Christmas cactus, remove it from the container and wash the soil from the roots. If most of the roots are black and slimy, it’s too late.
But if at least half of the roots are healthy and firm, trim off the dead bits, spray the roots with copper fungicide, and repot the plant.
Bonide makes an excellent copper fungicide that has helped me repeatedly over the years. If you’d like to grab some to keep in your gardening toolkit, visit Arbico Organics.
They carry it in 32-ounce ready-to-use, or hose end ready-to-spray, or 16-ounce hose end or concentrate.
2. Inappropriate Temperature
Anytime they are exposed to temperatures above 90°F or below 50°F, you run the risk of flower buds or leaves dropping.
Don’t assume that you’re safe just because you keep your home at a moderate temperature.
If your Christmas cactus is situated next to a single-pane window or an exterior door, it could be exposed to extreme temperatures often enough to cause problems.
Single pane windows don’t provide much insulation, which means they get hot during the heat of summer and they let in a lot of cold during the chilly winter days.
If you live in an area that experiences particularly frigid winters or sweltering summers, keep your Christmas cactus away from windows and doors.
Anywhere toward the interior of the house with supplemental lighting or skylights, or near well-insulated, multi-pane windows is fine.
3. Not Enough Light
Yes, they’re houseplants, and they can survive in the same light we have in our homes.
But Christmas cacti thrive in direct sunlight in the fall and winter, and direct light in the morning followed by bright, indirect light the rest of the day in spring and summer.
Anything less than that, and you run the risk that the plants will drop their cladodes.
If insufficient light is the cause, the plant will also be etiolated, which means it will be paler than it should be if it was kept in the correct exposure.
The fix for this cause is easy: move it into a spot with brighter light!
4. Nutrient Deficiency
I wouldn’t call Christmas cacti particularly greedy, but even if you’ve been feeding regularly, if the soil is old and depleted, your Christmas cactus might not be able to access the nutrients it needs.
You should be fertilizing your plant regularly starting in late winter or early spring. As soon as you see new growth developing, that’s when you need to start feeding.
Use a 10-10-10 or 20-20-20 NPK fertilizer once a month until fall.
Two weeks after you apply the fertilizer, add a teaspoon of Epsom salt dissolved in a gallon of water to add magnesium to the soil.
Holiday cacti are greedy for magnesium. Provide the typical amount of water you normally use and set aside any excess solution. It will last for several weeks.
Learn more about how to fertilize Christmas cacti here.
If you haven’t replenished the soil in the past five years or so, remove the plant from its pot and brush away all the soil.
Repot with fresh, new potting soil. Not sure what potting soil to use? Check out our comprehensive guide.
5. Pests
Sap-sucking pests like aphids, spider mites, and mealybugs can drain the plants enough that they might start dropping their leaves.
Before this happens, you’ll notice other symptoms like yellowing leaves and a sticky substance on the foliage known as honeydew.
Visit our guide to Christmas cactus pests to learn about identifying insect problems and how to get rid of them.
6. Too Little Water
It’s harder to underwater these plants than it is to overwater them. The paddle-like, succulent leaves store water well.
But if they go long enough without water, the cladodes will start to shrivel up, turn yellow or brown, and fall. The entire specimen will appear droopy, as well.
This probably won’t happen if you forget to water one time, but chronic underwatering will cause it.
The solution, of course, is to stay on top of your watering schedule while making sure you aren’t overwatering, which we’ll talk about next.
7. Too Much Water
It’s surprisingly easy to overwater a Christmas cactus, and when you do, leaf drop is sure to follow.
When you overwater, the roots in the soil basically drown. They can’t access oxygen, and they start to rot away. Aboveground, that means the plant can’t support its cladodes, and they get ejected.
Holiday cacti are true cacti, but they like a good amount of moisture, unlike their desert-dwelling cousins.
You should be allowing the surface of the soil to dry out before you add more moisture. When the plant isn’t blooming, you can leave it until the top half-inch of soil dries out.
The easiest way to avoid overwatering is to mount the plant on wood or wire. As epiphytes, they grow well this way, and it’s almost impossible to overwater mounted specimens.
If you’ve never mounted a plant before, it involves wrapping the roots in moss and fastening the plant to wood or wire to recreate the natural environment that epiphytes thrive in.
For information about how to rescue an overwatered Christmas cactus, head on over to our guide.
Keep it Together
There are precious few plants that provide you with bright color during the winter months. You don’t want them to be dropping buds and leaves and looking all ugly.
Holiday cacti are tough, so if you treat them right, you’ll be able to prevent leaf drop. And now you know how!
Were you able to solve your problem? If so, let us know what worked. And if you’re still struggling, drop us a note in the comments section below with what you’re seeing so we can try to help.
If you’re ready to expand your knowledge about holiday cacti, consider checking out a few of our other guides next:
