Why are My Christmas Cactus Leaves Turning Brown or Purple?
I’ll be the first to admit that my Christmas cactus sits pretty quietly in the corner of my patio for most of the year. Schlumbergeras are easygoing and long-lived succulents that prefer a bit of neglect if they’re being honest. If you give them a cozy spot with plenty of indirect exposure, they seem to get along just fine.
If you’ve noticed a change in your cactus recently, you may feel concerned about its health. When foliage starts to change color, it can mean that there is a negative agent at play. If your Christmas cactus has some brown or purple creeping in, it can be a bad sign, but not always.
If you’re familiar with succulents, you probably already know why some color changes happen. If not, it’s good to find out what’s okay and what the cause of the alarm is. Let’s talk about why your plant’s leaves are turning purple or brown and what you can do about it.
The Short Answer
Brown or purple leaves on a Christmas cactus are typically the result of stress. Not all stress is bad, though. A purple tint won’t hurt and even makes the plant prettier. Brown is a bad sign and means that there is a more significant stressor.
The Long Answer
The overall answer to the question of color-changing foliage is a simple one. It’s stress. However, not all stress is bad, and some can be rather pretty. Some can be a sign that the stress is beyond what the plant can tolerate, and you need to intervene quickly.
Brown
Brown leaves are always a signifier of a considerable problem. They are usually a sign that your Christmas cactus is failing to thrive and is on its way to that garden in the sky. If you catch it in time, you may be able to turn things around, but time is of the essence.
If you spot brown foliage, act quickly because procrastination can be deadly. The overarching reason for brown leaves is an overabundance of stress, which can take several forms.
Overwatering
Christmas cacti are succulents. While they go by the name cactus, they’re not quite as drought tolerant as all that. So they’re not true cacti, but they are relatively tolerant of dry soil conditions, and they’re easy to overwater if you’re not careful.
Their native range is southeastern Brazil, which receives a significant amount of rainfall. You’d think that would make them more tolerant of overwatering, but it doesn’t. This is an epiphyte. In terms of growth habits and needs, it’s similar to an orchid or anthurium.
Too much water sitting around the roots, and this epiphyte will begin to rot. Root rot and crown rot are the most common manifestations of overwatering in Christmas cacti. They are also difficult to reverse. Once you notice this issue, it’s probably too late to rescue the entire plant.
How to Fix It
Once the roots and crown have begun to rot, there is little you can do to preserve or rehabilitate these parts. If you remove it from its container and there are still some healthy roots, trim away the rotten tissue and repot it. Use well-draining potting medium, like soil mixed with perlite and orchid bark.
If the roots and crown are both affected, the best thing to do is salvage the healthy leaves and use them to propagate. Fortunately, this is an easy species to propagate, so you should be able to salvage some of it, and it will live to see better days.
Underwatering
If you’ve taken that neglect to another level, you may have a thirsty plant. This is less common, but I can’t tell you that I’ve never done it.
If you notice the foliage becoming wrinkled and dry, it’s definitely time for some water. If the thirst has gone beyond simple dehydration and the leaves are turning brown, it needs serious intervention.
How to Fix It
Water it! Watering a dehydrated Christmas cactus is the natural solution. If it’s in the early stages, you might see the leaves bounce back. If this happens, it’s a lucky sign, and your entire specimen should be okay.
However, if the leaves have turned completely brown, you’ll want to prune them after you give them a long trim. Those dry, brown leaves will never turn green again; instead, they will draw energy until they die back completely. To minimize the stress and amount of recovery your succulent has to do, trim off the brown foliage and allow it to channel that energy into healthy new growth.
Another consideration is how you have it potted. This epiphyte needs well-draining soil, but it should hold some moisture. Try repotting and mixing in more potting soil to add moisture retention.
Too Much Sun
Christmas cacti love plenty of bright light, but direct sunlight is not their favorite type of exposure. They grow on trees and shrubs, typically under a tree canopy. Again, think of the way orchids grow and the type of exposure they prefer.
If your cactus gets too much direct sun, it may develop sunburn. This will initially look white or gray, but ultimately, the affected leaves will turn brown.
How to Fix It
Move the pot out of the direct sunlight. Choose a spot where it gets a lot of light, but either filtered or indirectly. Trim off the brown foliage, as they will never turn back to green. This will help conserve energy that is better spent on new growth.
Nutrient Deficiency
An additional but rarer cause of discolored foliage is nutrient deficiency. That’s not to say that they don’t have significant needs, but the leaves will turn yellow long before they turn brown. This will be your indication that the plant needs attention in the form of fertilizer.
If the leaves are yellowing and looking shriveled, and watering didn’t help, they likely need some fertilizer. Christmas cacti prefer their soil to be slightly acidic. The lower pH breaks down nutrients, making them more available to the roots. Most potting mixes have a pH in this range, though.
Depending on which part is discoloring, different nutrients may be lacking. Sometimes discolored foliage is often a sign of nutrient deficiency. The most likely culprits are nitrogen, phosphorus, magnesium, and iron.
How to Fix It
Make sure to fertilize your Christmas cactus once per month for as long as it is putting out new growth. Stop fertilizing in late summer or early fall as it approaches blooming time.
Other Environmental Factors
Finally, there could be some other environmental factor at play in turning that foliage brown. A lack of humidity and a drafty location can cause stress to your plant, particularly if it lives indoors year-round.
How to Fix It
These epiphytes crave humidity. They grow in a humid climate and take in moisture from the surrounding air. For this reason, I leave mine outdoors for most of the year. A humidifier will work wonders, or you can relocate it to a bathroom window. A draft is easy to fix; just move the pot to a less drafty space.
Purple
Purple foliage is less of a concern and can even be something you grow to appreciate. Like many succulents, this one responds to mild stress by flushing a beautiful red-violet color. As long as you’re able to offer this stress in a controlled and measured way, you may decide to induce this color of your own volition.
Cold Temperatures
Along with its cool-season blooming period, this species needs to experience slightly cooler temperatures. To initiate blooming, it needs a few weeks of cooler weather in the 50-60°F (10-16°C) range. At temperatures below 50°F (10°C), Schlumbergeras will feel some stress, and they will produce that lovely purple color.
How to Fix It
Personally, I appreciate this characteristic, so I intentionally leave my plant outdoors for a few weeks longer than recommended. Never leave it exposed to temperatures lower than 40°F (4°C). Frost will kill it, so bring it indoors long before that first frost date.
Sunlight
We talked about sunburn turning leaves gray and brown, but there are other ways the sun will affect those leaves. With just slightly more sun than the plant needs, you’ll get some of that attractive purple blushing in the foliage.
I say slightly, though, because this is far trickier than controlling it with temperature. It’s easy to go from a little extra light to full-on scorched foliage. Once that happens, those leaves are gone.
How to Fix It
If you decide to do this intentionally, my advice is to go slow. Gradually move your Christmas cactus closer to the window and see how the leaves react. I find cold to be more effective in exacting this color shift.
If you notice this happening unintentionally and want to stop it, simply move the plant farther from the light. Don’t go too far, of course, as they like plenty of indirect exposure.
Final Thoughts
When it comes to Schlumbergeras, color changes can be good and bad. The severity of the changes and the specific color are important to pay attention to. If you notice leaves turning brown or yellow, there is an underlying issue that you should address. If, however, the color shifts to a pretty shade of purple, you might want to allow it just that bit of stress to bring out the beauty of the plant.
