Unlike other types of plants, cacti can tolerate abuse better than most plants. Still, you have signs that you should pay close attention to because it indicates a problem. One of those signs is a cactus that starts to shrink.
Why is my cactus shrinking? Cacti that shrink mean you need to water them more often. Water your cactus once a week to keep it healthy and away from shrinking. Pay special attention to bone-dry periods and times with higher temperatures when you want to water it extra.
If you’d like to learn more about why cacti shrink, keep reading because we will look at the reasons.
Why Do Cactus Shrink?
Cacti shrink as they lose too much water. They shrink down as a way to conserve water, and during this time, you may see how the cactus feels squishy or hollow. That means that it has begun to lose its water reserves. It doesn’t have the same plumpness because of a lack of water.
Can a Shriveled Cactus Be Saved?
If you notice a cactus that has begun to shrivel and shrink, you want to give it more water. Provided the damage hasn’t gone too far, it will return to its normal state. Be sure to keep watering it regularly to make sure that it remains in healthy condition.
Never think of a shrinking cactus as normal because it indicates a serious problem. You need to address the problem as soon as possible. Usually, shrinking cacti will plump right back up once they receive water. It doesn’t take long, but we’d advise you to know the cause because a shrinking cactus can give you cause for concern if it happens to be pests or root rot.
Not Giving the Cactus Enough Water
The chief cause of a shrinking cactus is the failure to water your plant, which often leads to this. During the dormancy period, which takes place in the winter, your cactus may begin to shrink, but as we said before, it will return to its normal state after.
Healthy cacti, however, don’t usually shrink too much unless it doesn’t receive water, or it has developed some type of disease. You may have the cactus in the wrong growing conditions as well.
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Especially during the spring and summer season, you should water your cactus once a week or even more if it looks like it needs more water.
Certain species of cactus, like the rainforest cacti species, such as epiphytes, Easter cactus and Christmas cactus all require more water than desert cactus species. Always know the type of cactus species that you have for the best results.
Pay attention to humidity as well because most cacti like between 40 to 60 percent humidity. Desert cactus don’t need humidity, however, except when tiny seedlings.
When you water your cactus, you should give it a thorough soaking because this mirrors its natural environment. You soak it one time, but you use soil with proper drainage that won’t hold in the moisture. Soil wet for longer than an hour and a half will damage the roots as it begins to experience root rot. Left untreated, root rot can kill your cactus.
Insects like the coccid soft scale insect can cause your cactus to shrink by sucking the juice out of them. Many times, this pest will cause the cactus to shrivel up and die. While one coccid soft scale won’t impact the health of your cactus, too many of them can kill it as it shrinks.
To kill the soft-scale insect, you can use neem oil. This works well against fungal diseases. Be aware of how as an oil on a plant, it will leave your cactus susceptible to sunburn, especially if you apply generous amounts of it. For that reason, you may want to apply the oil at night.
Mealybugs can cause a cactus to shrink as well. This bug will drink the juices of the cactus until it shrivels up and dies. Mealybugs will leave splotches and discolorations on your cactus. You can kill mealybugs with insecticidal soap. Beware of direct sunlight during this time because your cactus will especially be vulnerable to sunburn.
Shrinking from Fungal Diseases?
The cactus can shrink because of fungal diseases as well. Like we had previously mentioned, you can apply neem oil as a way to address this problem.
You can spot fungal diseases on a cactus easily because it will have a type of rot near the surface of the plant. Overwatered cacti that have moisture remaining in the soil will have the most problem here. As the fungus gains visibility on the outside, you will usually see the cactus shrink beforehand.
To prevent fungal diseases, use soil meant for cactus plants. In fact, I previously wrote about this in my article, “Can You Use Cactus Soil for Regular Plants?” It highlights the differences between cactus soil and regular plant soil, which you may find helpful here.
Fungal diseases can cause your cactus to ooze with soft sores on its surface.
Too Rootbound Can Cause Shrinking?
Believe it or not, cacti can become so rootbound that they don’t take in as much water or as many nutrients. A rootbound cactus usually happens when the plant outgrows its pot.
Expert Tip: Don’t use too big of a pot either because this can slow down the growth of your cactus. You don’t want to trade a shrinking cactus with a cactus that grows too slowly.
Most cacti experts advise that you re-pot your cactus in a pot one size larger than the current pot. You will want to re-pot your cactus every two to three years to prevent it from getting rootbound, which could cause shrinking.
You know your cactus has become rootbound when the roots show up outside of the drainage holes. Too many visible roots near the walls of the pot give you another sign of a highly rootbound cactus. As this limits how much water it can take in, the cactus will begin to shrink because it doesn’t get the amount of water that it needs.
Shrinking from Too Much Sunlight
Yes, believe it or not, the wrong environmental conditions can cause your cactus to shrink. You cactus may be shrinking because of too much sunlight.
In particular, pay close attention to the location. A cactus that sits in the window with direct sunlight has an increased risk of shrinking as the sun burns the plant. Beware of placing it near heat vents as well because this can also cause your cactus to shrink.
Sunburn can also cause your cactus to turn white until it dies. I wrote about that here.
Beware of the Type of Pot Used
In one example, someone used a plastic drinking cup to plant their cactus, and they began to see it shrink. You have a few reasons for this. First, a plastic cup doesn’t have the same amount of aeration as other types of pots.
We would advise that you use anything with a natural material because it dries out faster. You don’t want a cactus to have too much water in it for too long because it can cause root rot, which can also shrink your cactus.
Expert Tip: We would advise you to use a terracotta pot for cactus because it lets the water evaporate from the container faster than what you’d get with other materials. You don’t want the water to remain in the pot for too long.
You could either use terracotta, or you could use glazed. We wouldn’t recommend that you use metallic pots because the container will get too hot in the sun, and it will get too cold otherwise. As you know, heat can also cause your cactus to shrink.
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Beware of using glass as well. While you can use glass for a short time, make sure that it has drainage holes. In many cases, glass pots don’t have drainage holes, which can lead to root rot. In fact, it doesn’t make a good material for any plant, much less a cactus, which is susceptible to root rot.
In most cases when a cactus begins to shrink or shrivel, it happens because of a lack of water. The first thing that you should do is to examine your watering habits because this can resolve it right away. Once a week should give your cactus enough water to maintain itself. Beware of the other problems as well if that doesn’t seem to address the problem.
If you’d like to add to the cactus theme in your yard or garden, check out the Desert Steel Blue Agave – Metal Cactus Torch. This makes an awesome outdoor sculpture from metal art that was handcrafted. Many people will even think of them as live plants until you light them up.