Why Even Desert Succulents Like Some Shade

Assuming that landscape succulents (i.e. cactus, agave, aloes) love full sun is a common mistake that many desert gardeners make. Here’s why full sun can be hard on even the toughest sun-loving plants, and what to do if any of your succulents show signs of sun scald.

One of the most common mistakes that desert gardeners make is to assume that succulents of all kinds (cactus, agaves, aloes, euphorbias, etc.) can take as much sun as nature throws at them. While they may like some desert sun, or love full sun when grown in a pot on a window sill, that doesn’t mean they love the unrelenting death-star sun of the desert southwest.

The sun is so intense here that even cactus and agaves can get sunburned! Sun scald can appear as brown spots, bleached out patches, or overall yellowing.

While there are some exceptions, most succulents tolerate full desert sun but would be happier with some relief.

If you’ve ever visited a well-established botanical garden or a neighborhood that has lots of mature shade trees, you may have been surprised at how good all the plants look — even “sun-lovers” like cactus and agaves. I live near the “green” community of Civano, where you’ll find every kind of succulent imaginable thriving in fairly dense shade.

Surprisingly, compared to succulents that grow in the wild, plants in your yard face additional stressors and are more likely to get sunburned. Here are some of the reasons full sun can be particularly hard on landscape succulents.

Succulents Are Grown in Greenhouses

When you buy a new succulent, it was most likely grown in a greenhouse, probably in mild-weathered California. It’s not unusual for plants to spend their early days covered by 30 to 50% shade cloth.

Then, it’s moved to a nursery or garden center, where it still may be protected by a roof or shade cloth. Then you bring it home and plant it where it’s suddenly blasted by full sun. It’s a shock to the plant and a recipe for sunburn.

Many succulents can eventually tolerate full sun, but need a very gradual transition that can take months, not days. That’s why it’s generally recommended that you cover any newly planted succulents with shade cloth the first summer.

While sun scald is most common in summer, it can occur any time. I once put a potted golden barrel cactus in full sun in December, and it developed sun scald on one side!

Many Succulents Are Grown Outside Their Natural Habitat

Many landscape succulents are not native to the low desert, but we’re attempting to grow them outside their natural range.

Let’s take the case of agaves. There are 150 North American agave species, but only 40 naturally occur in the Sonoran Desert. The majority of these species grow in higher elevation grasslands and woodlands where the heat and sun is less intense. But plant one in a lower elevation desert, and it may struggle.

Succulent Orientation Matters

Another problem you may encounter is that succulents should be transplanted in the same direction that they were originally grown to minimize sun scald. The cells on the north side of a succulent are not used to getting as much sun as those on the south side. If you get this wrong, those sun-sensitive cells are highly susceptible to burn.

Better nurseries will mark the direction a succulent was grown. But if you buy one from a big box store, it won’t be marked, so you should take extra care gradually acclimating it to its new environment for the first year.

Succulents Can Have Misleading Labels

When shopping for plants, you’ll find that most succulents are labeled “full sun.” But full sun doesn’t always mean full sun here. This is an important distinction that most desert gardeners learn the hard way.

Imagine seeing a succulent in a garden center that’s labeled “full sun” and rated to be grown in hardiness zone 9. That same plant could be sold in San Diego and Tucson, both sunny, zone 9 cities. But many succulents that grow beautifully in San Diego’s full sun would be toast in Tucson’s.

Reflected Heat: Hotter Than the Sun!

Is there anything hotter than full sun? Yes! It’s called reflected heat.

A succulent in its natural habit does not face the additional burden of growing next to any man-made structures. On a sunny summer day, the surface temperature of a block wall or the side of a house will be around 180℉. The heat reflecting off a window can melt artificial turf — and it has a melting point of 175℉ – 200℉! I’m amazed that any plant can survive these temperatures.

What to Do if Your Succulents Are Sunburned

If you can see that a plant is getting too much sun, here’s what you can do, and what you should not do, right now.

• Provide temporary shade.
• Move gravel away from the plant base.
• Water appropriately. (Learn the right way to water cactus and other succulents here.)
• Don’t prune damaged growth.
• Don’t fertilize.
• Don’t spray with anything other than water.
• Don’t transplant, even if you think a new location will be of benefit.

I expound on the finer points of these steps in the article Heat Wave Survival Tips for Desert Gardens.

I hope you now have a better understanding of what your landscape succulents need and why “throwing shade” is one of the best things you can do to help them survive the scorching sun of summer.

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