If you’ve noticed that your cactus is suddenly turning white, don’t panic! There are several reasons why this could be happening, and most of them are easy to fix. In this post on why is my cactus turning white?, we will discuss the five most common causes of cacti turning white and how to remedy the situation.
*This post includes affiliate links. If you purchase something from the links, I will receive a small commission, at no extra cost to you. Thank you for your support!
Keep reading for valuable information on how to figure out what the problem is and how to save your beloved cactus!
Sunburn Causes Cacti To Turn White
Sunburn is one of the most common reasons why cacti turn white. If your cactus is in direct sunlight for too long (after not being in much sunlight for a while), the intense heat can cause the color to fade from green to white.
Unfortunately, these spots don’t tend to go away. Most of the white will be in spots that get the most sunlight. So if you see patches of white or the top of your cactus turning white, this sunburn is likely the cause.
Caring For A Sunburnt Cactus
The best thing you can do for a sunburnt cactus is to move it to a shadier spot, especially while it heals. If possible, try to find an indoor spot that gets indirect sunlight.
You can also try placing a sheer curtain or piece of cloth over the window nearest the cactus to protect it from the sun’s rays.
Prevent In The Future: The best way to prevent sunburn is to slowly acclimate your cactus to direct sunlight by gradually increasing the amount of time.
Cactus Turning White From Over Fertilization
Cacti are slow-growing plants and don’t need a lot of fertilizer. In fact, too much fertilizer can be just as harmful as not enough. If you’ve noticed that your cactus is turning white or the color is fading, this could be a sign of over fertilization, especially if you’ve fed it nutrients recently.
When you over-fertilize your cactus, the salt in the fertilizer can build up and cause the color to fade. This is because the plant is taking in more nutrients than it needs and the excess salt is being deposited on the surface of the plant.
Caring For An Over-Fertilized Cactus
If you think your cactus has been over-fertilized, the first thing you should do is flush the potting mix with clean water. This will help to remove some of the excess fertilizer from the potting mix. If you think it’s necessary, you can also repot your cactus into fresh soil, removing as much of the old soil as you can.
It’s also a good idea to not fertilize your cactus for a few months to give it time to recover.
Prevent In The Future: When fertilizing your cactus, always use a half-strength solution and be sure to water it thoroughly afterwards. It’s also a good idea to wait until the plant is actively growing before applying fertilizer. Cacti only need to be fertilized once or twice a year.
Cactus Turned White Because of Frostburn
Frostburn is another common reason for cacti turning white. This is especially prevalent for outdoor cacti. If the temperature drops suddenly or there is a frost, it can damage the plant. The frost will cause the water in the plant cells to freeze and expand, which can rupture the cell walls.
When this happens, the tissue of the plant will turn white or brown and eventually die.
Caring For A Frostbitten Cactus
If you think your cactus has frostburn, the best thing you can do is bring it indoors or into a warm area. If it’s too big to move or is planted in the ground, you can also wrap it in paper or cloth to help insulate it from the cold.
Once the plant has thawed out, check for any damaged areas. If the tissue is brown or black, it will probably need to be cut away, after a bit of time. If the tissue is white, it may still be alive and just needs time to recover.
Prevent In The Future: To prevent frost damaged cacti, make sure your cactus is in a location that won’t be exposed to sudden temperature changes. If you live in an area that gets frost, it’s also a good idea to wrap your cactus in paper or cloth to insulate it from the cold or bring them inside for the colder months.
Cactus Turning White From Pests
Pests are another common problem that can cause cacti to turn white. Mealybugs, scale, and moths are all common pests that can infest cacti. Mealybugs are small, white insects that feed on the sap of the plant. Scale are small, brown or black insects that suck the sap from the plant. Cactus moths are small, winged insects that lay their eggs on cacti, and when hatch, burrow into the cactus.
If you’re mostly seeing small white spots on the cactus, this is more likely bugs are the issue.
Caring For A Pest-Infested Cactus
If you think your cactus is infested, the first thing to try to figure out what the pest is. You can then look up how to get rid of that specific pest. In most cases, you’ll need to use an insecticide or pesticide.
There are also a few home remedies you can try, such as using rubbing alcohol or neem oil.
Prevent In The Future: To prevent pests from infesting your cactus, make sure to inspect your plant regularly. Overwatering or humid spaces can also lead to pest infestations of plants. So try to keep your cactus in a well ventilated, fairly dry area. And, if you see any bugs, remove them immediately.
Cactus Turning White From Overwatering
One of the most common reasons for cacti turning white is from overwatering. When a cactus is overwatered, the roots start to rot and the plant can’t get oxygen or nutrients from the roots. This can happen because the plant is sitting in water or because the potting mix doesn’t drain well.
(Read more about how often you should water your cactus, and why is my cactus falling over?)
My Cactus Is Turning White From Rotting
Rotting is another common problem that can cause cacti to turn white. This is usually caused by root rot, humidity, or water being on the actual cactus. Too much water can cause the roots of the plant to start to break down and rot. This can also happen if the potting mix doesn’t drain well. If your cactus is also shrinking, this is likely a sign of it rotting.
Caring For A Rotting Cactus
If you think your cactus is rotting, the first thing you need to do is feel the soil and see if it’s soggy. And take a look at the roots. If they’re brown or black, they’re probably already dead. If the roots are white, you may still be able to save the plant.
Trim away any dead or mushy roots and repot the cactus in fresh, well-draining potting mix. Be sure to not water the cactus for at least 2 weeks.
Prevent In The Future: To prevent your cactus from rotting, make sure you’re not overwatering it. Allow the plant to dry out completely between waterings and make sure the potting mix drains well. You can also add some sand or gravel to the potting mix to help with drainage.
And be sure to keep your cactus in a dry, ventilated area.
Final thoughts For Why Is My Cactus Turning White
The reasons stated above are the most likely cause of why your cactus turned white. Now it’s up to you to figure out which of these is most likely the cause. And then take steps to save your cactus, and prevent this in the future!