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How to Protect Succulents from Frost

Frost cloth protects jades and other vulnerable succulents in my garden

Frost cloth protects jades and other vulnerable succulents in my garden

Depending on the type of succulent, how low temperatures drop (water freezes at 32 degrees F), and how long the cold snap lasts, “frost tender” succulents may show damage just on leaf tips or collapse into mush.

When moisture in the cells of a vulnerable plant freezes, it expands and bursts cell walls. A few succulents have a built-in antifreeze, and survive temperatures well below 32 degrees F—below zero, in fact. But these are the exception, and tend to be in the genera Sedum and Sempervivum.

Crassulas, aeoniums, euphorbias, and kalanchoes are among the most tender succulents. The majority of aloes, echeverias, cacti and agaves can go a few degrees below freezing for a short period.

Unlike most agaves, thin-leaved Agave attenuata is the canary in the mine shaft where frost is concerned. After a brief exposure to 32 degrees, it looks like this.

Unlike most agaves, thin-leaved Agave attenuata is the canary in the mine shaft where frost is concerned. After a brief exposure to 32 degrees, it looks like this.

Check the forecast, and if there’s a frost advisory for your area, cover susceptible plants with frost cloth (sometimes called garden cloth, frost blanket or floating row covers) or old bedsheets.

When determining if a tender succulent needs to be covered, I sometimes stand over it and look up. Plants beneath eaves or tree branches are not as vulnerable as those open to the sky.

Cold air is heavier than warm, and flows down slopes and collects in low spots. Consequently, succulents in swales are more at risk than those atop berms.

You may have heard that Christmas lights raise the temperature a few degrees. Yes, if they’re the old-fashioned kind. Those sold nowadays (LEDs) don’t generate heat.

Wait until spring to trim damaged tissue. It’ll help protect the plants from further damage.

Watch how I cover my own tender succulents in my new video, “Protect Your Succulents from Frost.”

Will Frost Hurt Your Succulents?

Succulents from certain parts of the world, notably lower elevations of South Africa and Madagascar, are vulnerable to freezing temperatures. If the forecast is for temperatures below 32 degrees F, throw a sheet over your crassulas, kalanchoes, aeoniums, stem euphorbias and aloes before nightfall and remove it in the morning. See how I do it in my own garden in this video, Protecting Your Succulents from Frost.

Frost that nips your succulents may turn their leaves brown and unsightly. How do you know if a plant is worth keeping? It may depend on how patient you are. Even badly damaged succulents are surprisingly resilient, but it may take months before they look good again.

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Temperatures below 32 degrees caused the fluid in this aloe’s cells to expand and burst, irreparably damaging the tips of many of its leaves. Luckily for the plant, those same leaves protected its core, which is still green and viable.

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If you decide to try and salvage a succulent with this sort of damage, wait until the weather warms in spring, then snip off the dead tissue. Because new growth forms from the center of the rosettes, pretty soon the old leaves will be barely noticeable.

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And now you know that this is one succulent that needs covering next time there’s a frost advisory for your area. Here’s how my garden looks when temps are predicted to drop below 32 degrees F.

Notice that Agave attenuata tucked beneath the tree on the left? It’ll be fine because the tree will protect it. The plants you have to worry about are those that are out in the open, with nothing above them. I sometimes stand over a succulent and gaze upward. If there are no tree limbs or eaves directly overhead, it gets draped. (I use old sheets. Several years ago a nongardening friend, stopping by for a visit, asked if I was doing my laundry.)

How do you know if you live in a frost-free area? Your neighbors grow Agave attenuata in their gardens, and the plants look fine. In my garden, this soft-leaved agave is the canary in the mineshaft where cold is concerned.

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It’s the first plant to show damage from frost in winter. A lot of succulents can handle cold below 32 degrees for short periods. But Agave attenuata will look like this the next day. This is a nuisance, but fortunately not fatal.

Agave attenuata cropped

See the healthy green part of each leaf? Wait until spring, then use scissors to trim off the tissue-paper-like frozen tips, cutting each leaf to a point. When you’re done, the damage will be barely noticeable. By summer new growth will have hidden the short lower leaves.

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What about a succulent that has frost damage only on its leaf tips? Don’t bother to trim them. It’ll lose those oldest leaves in a few months, anyway.

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Kalanchoes tend to be quite frost-tender. One similar to this melted to the ground in my garden at 27 degrees, and I assumed it was a goner. Fortunately I didn’t dig up the damaged plant and discard it, because a few months later…

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…it came back from the roots.

Jade plant is another widely cultivated succulent damaged at 32 degrees. The leaves turn squishy and putty-colored. This is not pretty, but if the plant’s stems are firm, it will recover and grow new leaves.

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Actually, the jade plant in the photo was not a victim of frost. You know the term “frost burn?” This plant actually was burned…by a wildfire. The only indication that it wasn’t “burned” by frost is that frost tends to damage the top of a plant. This one was scorched on the side closest to the fire. (Which just goes to show, succulents cook rather than burn, but that’s a different post.)

If you live in an area where you can’t grow most succulents in the ground because it gets too cold, take heart…there are varieties that will do well for you. I recommend this excellent book: Hardy Succulents by Gwen Kelaidis, photos by Saxon Holt.Screen shot 2016-01-05 at 7.59.00 PM