Some of my cacti have recently turned yellow. This has never happened to me before, and I’ve always had good luck with my cacti. So I did some quick research and discovered why they turned yellow and what I could do about it.
Why do Cacti Turn Yellow?
To begin with, there could be multiple causes for the plant’s yellowing. Sunburn is the most common and likely cause of the cactus turning yellow from the top. It may appear ironic given that we think of cacti as sun-loving desert plants.
However, not all cacti thrive in direct sunlight, and some prefer light or partial shade. Cacti purchased from a store or nursery may also get sunburned if they are not used to bright outdoor lighting.
If this is the case, simply give the plant some partial shade during the hottest days of the year, and it should recover. It would also be beneficial to learn about the lighting requirements of the cactus. Some plants thrive in full sun, while others thrive in light shade.
However, if the cactus is turning yellow from the bottom rather than the top, the situation is usually more serious. The most common cause is excessive moisture and, worse, root rot. This is when you notice yellowing at the plant’s base that quickly spreads to the top.
When touched, the plant will become soft and mushy. These are symptoms of root rot, which makes it more difficult to treat and save the plant. The plant may have stayed wet for too long as a result of either too much water or the soil not drying quickly enough, or both.
It is also critical to inspect the soil you are using for your cactus. Overwatering isn’t always the only cause of constantly wet soil. The soil itself may not be drying quickly enough, keeping the plant’s roots constantly wet. Make sure you’re working with a quick-draining soil.
Commercial cactus potting mix mixed with perlite or another porous material for drainage would suffice. To begin, a solution of 2:1 potting mix and perlite would be ideal. Others prefer to improve drainage by adding coarse sand.
Exposing a cactus to extremely cold temperatures in the winter and keeping it wet, as I did with my plants, is one of the most damaging things you can do to it. We just had a very cold and wet winter season, and some of my cacti did not fare well.
Because I live in Northern California, I keep all of my cacti outside all year and let them weather the rain and cold. They are usually fine, but this year’s rain was above average, and my plants became waterlogged.
Cacti prefer to stay dry during their dormant period, which occurs during the colder months. And some cacti are not naturally cold hardy. Exposed to wet and cold conditions can be fatal to the plant.
Insect infestation is another less common cause of yellowing. Examine the cactus carefully to see if there are any creepy crawlies around the plant. Spider mites are small red bugs that look like miniature red spiders.
A severe spider mite infestation can be fatal to the plant. Spray rubbing alcohol on the affected area immediately. Separate the pest-infested plant or it will spread quickly.
To avoid sun damage, keep the plant out of direct sunlight after spraying with alcohol.
Aphids and mealybugs are two other common pests. Check for white fuzz around your plant because this is a sure sign that you have mealybug infestations. These pests suck on the plant’s tender parts, causing damage. Wipe the plant with rubbing alcohol to get rid of them.
To kill the bugs, spray the plant with soapy water. You may also need to repot the plant and remove it from the soil to ensure that no eggs are hiding and ready to hatch.
Yellowing can also occur when newly purchased plants are repotted into a new pot with fresh soil. Shock and changes in watering techniques can cause the plant to turn yellow. When repotting, make sure the pot you’re transferring the plant to isn’t much larger than the nursery pot it’s currently in. A small plant, in particular, can be shocked by too much soil.
Reasons why Cactus are Turning Brown
A cactus can turn brown instead of yellow. The most common cause of this is age, which is referred to as corking. Corking occurs naturally as a cactus matures.
It starts at the plant’s base, where it touches the soil, and can move up slowly or stay in one spot. Corking imparts a woody appearance to the plant. Otherwise, the plant appears to be in good health and is firm to the touch.
When the plant turns brown and becomes mushy or soft to the touch, you have a different problem. This is usually an indication of rotting, disease, or both. Rot can enter the plant through the roots of a cactus that has been constantly wet.
Fungal disease or pest infestation can also cause a cactus to turn brown. Browning can occur from various parts of the plant and will not be firm to the touch, but will feel soft and mushy.
Why is my Cactus Drooping and Shriveling?
Underwatering is the most common cause of cactus shriveling and drooping. The plant will appear wrinkled and soft to the touch. A healthy cactus should be firm and not droopy and soft to the touch.
While underwatering is the most common cause, overwatering can also cause the plant to droop and shrivel. This is usually accompanied by yellowing from the plant’s base, which aids in determining the cause of the drooping.
Why Does the Cactus Feel Soft?
When a cactus becomes soft, it is not always due to overwatering or rot. It can sometimes be an indication that the plant is severely dehydrated. Cacti and succulents have large water storage capacities and can withstand prolonged droughts. This is not to say that they do not require water.
Cactus plants enjoy a refreshing drink of water, particularly on hot summer days. They begin to deplete their water storage if they are without water for an extended period of time. This is when you notice them softening.
The plant can also turn yellow due to a lack of water or being overly dry. The plant will usually appear shriveled or wrinkled as well. If this happens to your plant, give it a good watering and it should recover in a day or two.
The damage to the plant is more severe when there is yellowing from the bottom and the plant feels soft and mushy. The roots of the plant are rotting. Overwatering is the most common cause of this, or the plant has been exposed to extreme cold, extreme heat, or all of the above.
Related: Are Succulents and Cacti the Same?
Can you save an overwatered cactus?
Yes, but it depends on the extent of the plant’s damage. The less severe the damage, the better the cactus’s chances of recovery. The first step in dealing with an overwatered cactus is to stop watering it. If you have a weekly watering schedule, for example, stop doing so and allow the plant to dry out and recover.
Steps on how to save an overwatered cactus:
- Clean the roots of the cactus after removing it from the wet soil.
- Allow the plant to completely dry out for at least three days to a week.
- Place the plant somewhere bright and dry, but out of direct sunlight, to avoid burning it and completely drying out the roots.
- Replant in a suitable well-draining potting mix once dry, but do not water immediately. Allow 2-3 days before watering. Water thoroughly and then wait until the soil is dry before watering again. Avoid overwatering in the future.
Can you still save a dying, rotting cactus?
Again, it is dependent on the extent of the plant’s damage. The more damage and rot the plant has, the more difficult it is to save. It is best to try to save the plant as soon as you notice rot developing.
When the rot is severe, there is little you can do. It also depends on the plant’s maturity and establishment. Plants that are larger and more established have a better chance of survival than smaller, baby cacti.
If you want to save your plant after rot has set in, you must act quickly.
Steps on how to save a rotting cactus:
- Examine the cactus for the extent of the rot. Find plant parts that can be salvaged, such as firm, green parts.
- Remove any mushy or rotting parts, including the roots. Save any green, firm, or viable plant parts. When you cut the plant, you’ll know whether it’s viable or not. If the inside has green parts rather than brown or black, these have a chance of survival and can be propagated to start a new plant.
- Saved parts should be stored somewhere dry and out of direct sunlight. Allow to dry for a few days to several weeks, or until all cuts have calloused and sealed. (Optional: apply some sulfur powder to the cactus wounds.) Sulfur powder, which is commonly used as a fungicide, can help prevent infection.
- Make a potting mix that drains well. I usually use a cactus mix with perlite. To improve drainage, you can also add coarse sand to the mixture.
- Stick the wounds in soil once they have healed and dried.
- When the soil feels dry, water it. To avoid burning the plant, keep it out of direct sunlight until it has fully rooted.
How to prevent this from happening again?
Learn the fundamentals of cactus care. Make sure the soil drains well. Only water when the soil feels dry. Before watering again, the top inch of soil should feel dry. Provide plenty of light while taking care not to burn the plant.
Sometimes the plant is too far gone to be saved, and there is nothing you can do. It isn’t much you can do to save the plant once the entire plant tissue becomes mushy. Don’t berate yourself for it.
You can always try again and see if your luck improves. It’s sometimes not even your fault. The plant could have died before you got your hands on it.