Do cacti need sunlight? While most species of cacti don’t need direct sunlight to thrive, they still do require some sun. They are like other succulents, they will do well when positioned in good light, whether direct sunlight or not. Cactus is known for its ability to store water and be resistant to drought. This is the primary reason they are considered desert plants.
If you’re growing plants indoors, position them on a window that faces south to provide them with access to bright light. If you are growing them outdoors, choose an area that has partial shade to keep them protected from intense light.
Depending on where the species originated, some of them can’t handle full, direct sunlight, as they will suffer from damage and sunburn. However, there are some species that have adapted to handle direct, intense sunlight.
Due to the fact that most of them do well in arid/semi-arid areas, gardeners typically assume that they need direct exposure to bright, intense heat to thrive. However, this may not necessarily be the case. We will explore the answer to this question in this article.
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Do Cacti Need Exposure to Direct Sunlight?
Of course, cacti do typically fare better when they receive lots of exposure to light – but they do need to be protected from the intense heat and light from direct sunlight. If you expose them to too much heat/light, it can cause significant damage.
Too much exposure to direct sunlight can cause sunburn, which results in scarring or even death. If you want to avoid this, it’s good to slowly acclimate your plants to the intense sunlight before full exposure.
You can start by placing them in an area that has partial shade and then slowly bring them more into the sunlight until they are fully acclimated to the sun/heat. Morning sun is best to start with since it is less intense and then slowly work your way to the more intense sunlight in the afternoon.
You may also consider placing cacti under the shade of other plants before moving them and exposing them to direct sunlight. The primary goal here is to avoid traumatizing the plant by increasing sun exposure slowly. If you do it too quickly, you may sunburn and/or permanently scar the plants.
Due to the simple fact that different areas of your outdoor space get hit by direct sunlight at various times, you may need to do some trial-and-error to determine which location is best for your plants.
Also, if you have sun-hardy cacti that you’ve been raising indoors, they are susceptible to sun damage or sunburn when moved abruptly outdoors. Therefore, it’s critical that you take your time and acclimate the plant to the heat and light before leaving them in direct sunlight all the time.
Newly Propagated Cacti
Plants that are newly propagated are not going to do well in direct sunlight. They need some time before they are put under direct light.
There are a few species that prefer shade over direct sunlight. Newly propagated cacti are much more likely to get sunburned and scarred. However, keep in mind that grey, blue, and red cacti with lots of spines love direct sunlight.
Some will do very well in the morning sun, while others will do better in the afternoon. Again, pay close attention to how they are responding to the exposure.
Check out our guide on How to Propagate a Cactus here!
How Many Hours of Sunlight Do Cacti Need?
As a general rule, cacti need about 4 to 6 hours of sunlight each day to thrive. They love being in bright, sunny locales. If they are not receiving adequate exposure to light, they may display a wide array of signs.
The most common sign that they’re not getting enough sunlight is elongation/etiolation, which is a process by which plants stretch to seek more light. While this seems like a good mechanism for self-adaptation, it results in poor growth and produces weak stems.
If cacti plants are not receiving adequate exposure to sunlight, they may become pale or go back to their original green color. On the other hand, plants that are getting adequate sunlight exposure showcase a wide variety of vibrant colors.
Once again, if you’re growing your plants indoors, make sure to position them on a south-facing window to provide them with access to direct sunlight and heat.
Can Cacti Receive Too Much Sun?
The short answer is yes. If plants are exposed to too much sunlight, they can experience sunburn and damage. Unfortunately, sunburn can happen quickly during heat waves or when temperatures increase significantly. On the other hand, sometimes it happens more gradually.
The first sign that your plants are sunburned is yellow/brown spots on the plant. If you notice the signs of sun damage early, you can easily remedy these effects and prevent further damage to the plant.
When you see damage, simply relocate the plant to a shady area, or place them near taller plants to protect them from excess sunlight. If you don’t do anything to take care of your plant after noticing sun damage, some plants will eventually die. But, some will adapt to the heat and survive. However, you shouldn’t take chances- provide your plants with necessary protection when temperatures increase.
Can Cacti Survive without Sunlight?
Since it is possible for a cactus plant to receive too much sunlight, you’re probably curious as to whether it’s possible for a plant to survive without sunlight. The truth is, cacti are just like other plants, they do need some sunlight in order to survive. The plant absorbs the light, which triggers chemical reactions that help the plant produce energy and food.
While cacti can survive in low light conditions for a while – after a few days, they will begin to show signs of stress, including stunted growth and etiolation. In addition, they will begin to look pale and no longer display vibrant colors.
If given too much water and not enough light exposure, plants may end up succumbing to root rot. If you don’t take steps to fix the problem, it will begin to rot from the roots, eventually dying. Once root rot sets in, it’s hard to save your plants.
How to Keep Cacti Alive During Heatwaves
According to some experts, climate change could be causing more frequent weather extremes in various parts of the world. Some regions have heat waves, which can be challenging to deal with since they can last for several days or even weeks and can cause harm to cacti plants.
If you leave them unattended, you risk losing your cacti. So, what can you do to protect them? Here are a few steps you can take to ensure that your plants survive the extreme heat.
Provide them with shade
When you know a heatwave is coming, the best thing you can do is prepare ahead of time. Try to find a good shelter for your younger, smaller, fragile cacti. If possible, bring them indoors, but if not, find a shady spot in your garden for them.
While your taller, mature plants are likely acclimated to the heat and may be fine, they should still be monitored.
If your plants are in the ground and you can’t move them, consider covering them with a shade cloth.
Avoid repotting
One thing is for sure, a heatwave is not the most ideal time to repot your plants. Even repotting a mature, well-established cactus can put stress on the plant. Therefore, if you do it at a time when the weather conditions are extreme it will only make the situation worse. If you must repot, wait until conditions have stabilized before you do so.
Don’t fertilize
While it’s true that fertilizing your cacti will make them grow quickly and thrive, you should only do it during the right time/season. Ideally, fertilizing should happen during the spring when the plant is actively growing.
During a heatwave, your plant is focused on surviving, not growing. So, you will only cause damage by introducing extra nutrients during this time.
Conclusion
While it’s true that cacti do quite well when placed in areas that receive lots of bright sunlight, this doesn’t mean they need to be consistently exposed to direct sunlight. Some plants are susceptible to sunburns and/or sun damage when placed in direct sunlight.
If you live in the northern hemisphere and you are growing your cacti inside, consider placing them in south-facing windows. This is a great position that provides them with adequate access to sunlight.
Of course, the optimal amount of sunlight a cacti requires depends on the species. Some do very well in low light conditions. Others need to be in bright spots. Whatever you do, make sure that you are taking care of your plants in the way that is appropriate for them.
Take your time and do your research before you get into growing cacti. You’ll be glad you did.