There is a misconception out there that cacti plants love excess sunlight because most of them grow in deserts. In fact, a significant number of gardeners believe that a cactus plant will happily sustain full blazing sunshine all day long, and nothing will happen to it. But, is it true? Are these succulents resistant to sunlight, no matter how severe it is? We shall find out in a moment.
So, can a cactus get sunburn? Yes. Although these plants are fairly hardy, they are still susceptible to a wide range of diseases and environmental stress. Exposing your cacti to high-intensity sunlight that they cannot handle will result in sunburn and shriveling of your plants.
And the most unfortunate thing is that sunburn is not only unsightly but also dangerous to your plant’s health. Severe sunburn can cause irreversible damage to your plant, leading to death.
In this blog post, we discuss everything you need to know about cacti plants and sunburn. How does sunburn occur? How can you know that your plant is experiencing sunburn? How can you stop it, and how can you prevent it from happening in the future? So, let us get started.
Can a Cactus Get Too Much Sun?
All plants are living things, and they need plenty of food to survive. Sunlight is an essential requirement in the process of photosynthesis, which helps every green plant to manufacture food. Technically, it means that if your cactus doesn’t receive sunlight, it won’t synthesize food, and it will eventually die.
But, there is a limit to how much sunlight every plant species requires. If the amount of sunlight provided exceeds a certain threshold, it is no longer useful to the plant. Instead, it becomes damaging, and unless you take measures to save your plant, it will eventually die.
It is true that cacti plants, just like other succulents, love sunshine and can withstand direct sunlight for certain amounts of time. In fact, most cacti species tend to thrive in relatively warm temperatures of between 60oF and 80oF. Some species, such as the Old man cactus, will still do well in higher temperatures.
However, when you combine high temperatures and direct sunlight, then your plants may start straining to contain the intense heat and will start running into trouble. In the same way, you would be comfortable sitting under direct sunlight for an hour when the temperature is maintained at 70oF but will quickly take cover when it rises to 80oF.
It is the ultraviolet (UV) rays and the strong intensity of sunlight that will burn your cactus and not actually the heat. But still, relatively higher amounts of heat can also lead to rapid water loss and higher internal temperatures, which makes your plant more susceptible to physical damage, including sunburn.
How Do You Know Your Cactus Is Getting Sunburned?
When a cactus is exposed to too much sun, it will start to develop internal stress. However, if you manage the exposure effectively, the plant may adapt to the extra sunlight and heat by producing some brightly colored pigments. If you fail to manage the exposure effectively, then it will become sunburned.
One of the earlier signs of sunburn is the development of patches on the leaves of the plant. If only a section of the plant is exposed to excessive sunshine, there may only be a few parts of the plant showing symptoms of sunburn.
Depending on the severity of the burn, the patches may be brown, black, or tan in color. Typically, the more severe the sunburn, the darker the discoloration will be.
A severely sunburned cactus may also be permanently scarred. The dark, discolored patches that develop on sections of your plant that have suffered sunburn are usually permanent. But it takes some time before the damage becomes irreversible.
If you notice the appearance of dark scars on different parts of your cactus, be sure to touch the spots and feel their texture. If they are slightly dark, but their texture feels smooth, then it is only a sign of impending sunburn, and the damage is reversible at this stage.
All you have to do is move the plant to shade before the actual permanent scarring occurs. With time, your plant will heal, and the scars will disappear.
It is also good to mention that a cactus may respond to excess sunlight and heat by changing from green to yellow-green. This is usually a sign of stress and a pre-sign of potential sunburn. Although this change doesn’t leave behind any scars, the effects can be quite severe if you don’t act quickly.
The moment you notice the green-yellow color, consider moving your plant to shade and let it rest there for some time. The green-yellow sections will disappear when the temperatures drop, and the stressed tissue of the plant will return to normal.
Why Is Your Cactus Getting Sunburned
At this point, you might be wondering why cacti plants suffer from sunburn in the first place. Well, there are two major causes of sunburn that you need to know.
Sudden change in growth conditions
Although most cacti species love sunlight and a little more heat, they need time to adapt to it. Keep in mind that almost every cactus plant you will find in your local store is grown in a greenhouse. This means that the growth conditions that these plants are accustomed to are consistent.
When you bring your new cactus home and put it in direct sunlight, the conditions change drastically, and the result can be unpleasant. Exposing your plant to full and direct sunlight at this point will only result in severe sunburn within a few hours or days.
Another critical aspect of growth you need to be careful with is moving your cactus from one place to another.
For instance, if your plant has been growing with one side facing south where it is exposed to maximum light and the other facing nothing which is shadier, then turning your plant 180 degrees could be a big mistake.
When the other side that has been in the shade for a long time is suddenly exposed to direct sunlight, it can develop severe sunburn within hours. If you want to turn your plant, do it gradually, giving the other part that has been in shade enough time to adapt to the new conditions.
Change in habitat
By now, you need to have understood the fact that the cactus family is large and features over 2500 different cacti species that grow in different habitats.
For instance, you will find the jungle cactus in tropical rainforests while the Saguaro will grow happily in the blazing heat of the Arizona desert. You will even find some cacti species in the high Andes Mountains of South America and the foggy coast of California.
What we mean is that before you go out and purchase a cactus plant, take time to understand where your preferred species is found and the general conditions it prefers to grow in. This way, it becomes a little bit easier to provide the right conditions because you already have a clue.
When you finally bring your cactus in, pay close attention to the growing conditions the plant has been in and try to simulate them in your home. Also, if you are bringing your plants outside after the winter season, be sure to introduce them to the spring sunlight gradually.
Caring for Sunburned Cactus
If you catch the sunburn before it becomes severe, you can save your plant from the irreversible damage.
The first thing you need to do is to get it out of direct sunlight. If you notice any yellowing on the surface of your plant and it is in full sun, be sure to move it even if you have to assume the task of taking it in and outside every day.
But we understand the fact that moving the plant is only possible if it is in a pot that is small enough to move. If you have a large cactus plant that you suspect is developing sunburn and you cannot move it, then try to cover it using a shade cloth during the hottest part of the day.
Secondly, keep your plant watered but be careful not to overwater it because it can lead to other problems. Typically, if a cactus is stressed or sunburned, it will go into a state of dormancy regardless of the season.
During this stage, the plant is going to cease growing and focus on repairing the damaged tissues and re-establishing itself. Frequent watering may help the cactus in the long run, but don’t be tempted to overwater it.
Lastly, strive to protect your plant from pests and other diseases. Keep in mind that if your plant is sunburned, then it is weaker and more susceptible to disease and pest infestation.
Therefore, take time to check for bugs and ants that may cause more damage than what the plant has already suffered from sunburn. If you notice signs of diseases or pest infestation, be sure to take appropriate action.
How to Prevent Sunburn in the Future
When it is time to move your cacti plants outside after spending winter indoors, you need to be careful with the process. Do it gradually to avoid stressing the plant. Typically, you should introduce your plants to increased levels of sunlight slowly over two or three weeks.
During the first few days, consider putting your cactus into full sunlight for just a few hours a day and slowly increase the time every few days.
Once the plant has received plenty of sunlight for the day, move it to a shady area, or if you cannot move it, cover it with a shade cloth. Moving your plant to a shady area or covering it during the hottest part of the day will help to prevent sunburn.
We hope you understand how to take care of your cactus to prevent sunburn. Caring for these succulents can sometimes be difficult, but you have to learn the tricks along the way. If you have got any questions or comments, please let us know in the comments section below.