Most succulents need the sun to grow well, but just how much sun can vary from one succulent species to another. Despite this need for sun, in some circumstances, succulents can suffer sunburn when exposed to the sun.
Our nursery grows over 200 different species of succulents in sunny Australia, so we see year on year what sun does to succulents in different seasons and what triggers a succulent to burn, even if it does not seem to be particularly hot. Below I’ll explain when succulents can suffer sunburn and what can be done about it.
When can succulents suffer sunburn?
- During heatwaves
- After sudden movements from shade to sun
- After long periods of rain in summer
- Behind glass
- Shade-loving succulents in the sun
Heatwaves
Heatwaves and direct exposure to strong sun’s UV are the main reasons succulents get sunburned. Just like our skin, succulent leaves can suffer sunburn on very hot days. The temperature at which succulents can start getting burned ranges from about 30C/86F-40C+/104F
While there are many succulent species that will survive exposure to hot, over 40C/104F sun without burning, others can die very quickly if exposed to direct sun during these kinds of temperatures. It can be a little difficult to ascertain which succulents will get sunburned as even plants within the same genus can have different sun exposure needs and tolerance.
If you’re interested in names of succulent plants that will likely survive extreme heatwaves you can see our article on the hardiest succulents for direct sun here.
To protect succulents from burning during a heatwave, either move to a shaded but bright spot for the duration of the heatwave or pitch a shade cloth over. We have another article here on how to protect succulents during a heatwave.
Sudden movements from shade to sun
Moving a succulent from a shaded position to sun without acclimatizing it first can cause sunburn, especially during the warmer months and in sensitive succulents. Even a short stint (a week) indoors or full shade can make a succulent less tolerant of sudden sun exposure.
When succulents are grown in too much shade they tend to grow wider, thinner leaves. Those that produce farina, the white, powdery coating on the surface that acts like sunscreen, seem to also have a thinner layer than succulents grown in sun. All of these things will make succulents more prone to suffering sunburn.
The hardier succulents are likely to survive a move without getting sunburnt, especially if the sun is not too strong, but others can suffer extensive damage.
The best way to prevent sunburn damage from moving is to stagger the exposure to the sun. Morning sun tends not to be too strong and so about 2-3 hours in the morning followed by bright shade for 4 or so days should get the plant used to the sun a bit. Increase the sun exposure by 2 hours every few days. Having said that, if it’s way too hot in the sun (over 30C/86F) do not move past the morning sun stage until temperatures are in their under 30C.
After long periods of rain in summer
Succulents can explode in growth after a good rain, but all of this new growth can make them more susceptible to sunburn once the sun comes out, especially if the first day after a rainy spell is very hot.
There are a few things that come into plain during rain. Firstly, the leaves become swollen with all the extra water, then some of the UV- protecting farina can get washed away and also the plants have effectively been in shade for a few days. Combined, all of this can result in succulent sunburn.
In my 10 years of running my succulent nursery I have only seen this happen in summer/ end of spring when hot and mostly in potted succulents. Here in Australia the temperatures can vary wildly and we can have a few days of solid rain in summer followed by tops of 40C/104F after the clouds have blown away. When the sun is not too hot, it is unlikely that the succulents will burn after rain. It can still happen with sensitive succulents, but it is unlikely.
Behind Glass
Glass will intensify heat that is radiating from the sun. If any succulents are immediately behind glass and the sun is shining through on a hot day, they are very likely to suffer sunburn.
This can happen to indoor succulents on windowsills, terrarium plants, plants in sunrooms or glasshouses. When the succulents a bit further away from the glass, sunburn is not very likely.
During heatwaves it is best to protect your succulents that are on windowsills or immediately behind glass by moving them a meter or so away from the glass. The intensity of heat will not be as bad.
In glass houses or even polytunnels that do not have shade-factor a 30% shade cloth placed over the top will prevent any burns.
Shade-loving succulents in the sun
Not all succulents love being exposed to sun all day long and can get burns easily even after 10 minutes in strong, afternoon summer sun. Succulents that prefer shade such as the Haworthia, Senecio Rowleyanus or Gasteria can suffer sunburn if exposed to too much hot sun.
Before you buy a succulent it is extremely useful to first look it up to establish what kind of conditions it is likely to flourish in. Not all succulents are created equal and knowing a little bit about your plant can be a matter of life and death.
Despite succulents being a hardy bunch i have heard countless stories from customers about how they killed a succulent simply by putting it in the wrong place (usually sun loving species indoors). But many have assumed that every single succulent loves being in the sun and have killed their String of Pearl or other shade succulent simply by ‘giving’ it sun on a hot day.
How do you know a succulent is sunburned?
Sunburned succulents can have dark marks or shriveled parts on the leaf that look like a bit of the top has been scraped off. In some succulents the sunburn is a whiteish colour.
You will know a succulent is sunburnt because of the marked leaves. Just like us humans succulents will also suffer discoloration and damage to their ‘skin’. In some succulents the marks will be lighter brown and can go up the scale to almost black in extreme cases. Along the dark burn marks, the leaf can be shrivelled too.
Some species will try protect themselves by closing the rosettes so as little of the leaf is exposed to the burning sun rays. I have seen this mostly in Echeveria species.
Sunburn marks can differ from one succulent to another. One can have burns just on the tips (or one tip) , while others can have them in the middle of the leaves.
Another sign of sunburn in succulents is a sunken leaf effect in the middle of the leaf. This mark can turn brown over time but initially it will look like a bit of the leaf has collapsed into itself and can also appear light in colour. String of Pearls (Senecio Rowleyanus), for example, often has white burn marks rather than brown. Many small leaves Sedum such as the Acre also appear white when burned by the sun.
Sunburn damaged leaves are very likely to eventually shrivel and die off.
In cases of extreme sunburn, when a succulent is exposed to over 40C/104F direct sun, the plant may not even get time to burn and the shock of this immense heat and UV radiation will cause all the leaves to fall off. The plant can also start cooking slowly, especially if in a dark pot. In such cases, succulents are likely to look like they have rotted and have translucent, mushy leaves.
Will sunburned succulents die?
Whether a sunburned succulent dies will depend on the severity of the damage. When there are only brown sunburn marks it is likely the plant will pull through. If the leaves are rapidly falling off or are mushy there is a strong chance of it collapsing.
While I have seen even the most severely burned succulents pull through and grow out of their burns, in some cases, usually in young plants or succulents that are sensitive to strong UV, the death can be very fast even at lower temperatures.
Can a succulent recover from sunburn?
A succulent can recover from sunburn and continue to grow and be healthy, but the sunburn marks do not heal or go away. New foliage will eventually replace sunburned leaves and in time they will not be as visible.
Some species of succulent plants can recover extremely quickly from sunburn and new leaves and branches will completely mask the burned ones. Burned leaves also tend to fall off at some stage, especially if the burn was severe.
In others the recovery can take a few months and even a year, especially in slow growing or rosette shape succulents that do not produce many offsets (mostly succulents in the Echeveria genus).
How do you fix/treat sunburned succulents?
To fix or treat sunburned succulents they need to be first taken out of strong sun or protected by creating shade so they don’t burn further. If dry, they can be watered.
Treatment will largely depend on the severity of burns and species of succulent. If only a couple of leaves are burnt, they can easily be pulled off and the plant will not look much different. But when most of the leaves have burn marks it can be quite difficult to restore the succulent to its former glory.
If any of our plants get burned by accident and the damage is bad I’d usually cut whole branches off or ‘behead’ rosette growing plants. The burned bits can still be re-potted as cuttings and should grow to new plants, leaving the sunburned leaves behind, hidden under new growth. The original plant will regrow as well. To see how to behead a succulent, see this article.
Can indoor succulents get sunburned?
Indoor succulents can easily get sunburned if they are on a windowsill or close behind a window. On hot, sunny days the sun’s rays will only intensify once they pass through glass and the succulent on the other side can suffer sunburns in a matter of minutes.
Although it is incredibly important that indoor succulents have lots of bright light, in summer it is very possible they will burn if close enough to the window if direct sun passes through. If you can feel the heat on your skin, then succulents can feel it as well. It is also very important that the right succulent is chosen if you’re planning on growing it indoors as many will simply not survive long-term. To see the best succulents for indoors, you can read this article.
Burns are unlikely during the cooler months or in morning sun but once the sun is high up in the sky or in the afternoon, its UV rays can be deadly.
Are succulents ok in direct sun?
The majority of succulents are ok in direct sun and, in fact, need to be in direct sun to grow well. However, during extreme heatwaves few succulents will be happy in direct sun. The only time succulents will not be ok in direct sun is during extreme heatwaves or if they are one of the species that prefer shade.
While many succulents come from dry and hot areas, temperatures we are seeing now in summer can rival those of the desert. In fact, not very far from where our nursery is (10km) a Western Sydney suburb was the hottest place on Earth one day in January 2020. In 2021 a heat dome in the US and Canada has broken records.
Just like humans and animals, plants, even succulents can suffer and die in these conditions. So during unusually hot spells, do take extra care of your succulents and other plants. Pot plants should be moved to shade and shade can be created over garden plants using sticks and shade-cloth or some other cloth.
Then there’s also succulents that do not like growing in a lot of direct sun. These can be random species from otherwise sun-loving genera or whole genera such as Haworthia. Research is the best tool in identifying these plants.
To conclude, most of the time the great majority of succulents will be just fine in direct sun, it is only the extremes that can sunburn or kill them.