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Frost and Succulents: What You Need to Know

Frost and Succulents: What You Need to Know

Depending on how long temps stay below freezing (32 degrees F), “frost tender” succulents may show varying degrees of damage. When moisture in the cells of a vulnerable plant freezes, it expands, bursts cell walls, and turns leaves to mush. In a “light frost,” leaf tips alone may show damage. In a “hard frost,” temps stay below freezing for hours, which can collapse entire plants. Succulents typically don’t regenerate from roots.

Crassulas, aeoniums, euphorbias, and kalanchoes are among the most tender succulents. A few succulents have a built-in antifreeze that enables them to survive temperatures well below 32 degrees F—below zero, in fact.

Should you be worried about your outdoor succulents in winter? It depends on where you live. See “Cold Weather Care for Outdoor Succulents, By Region.”

Your area is frost-free (lucky you!) if…

Agave attenuata grows in gardens, and the plants look like this year-round.

Cold Weather Care for Garden Succulents

Agave attenuata is the first succulent to show damage from frost in winter.

In my garden, this soft-leaved agave is the canary in the mineshaft where cold is concerned. A lot of succulents breeze through a brief frost (less than an hour), but leaf tips of Agave attenuata show damage right away.

Frost and Succulents: What You Need to Know

After a brief exposure to 32 degrees, Agave attenuata will look like this.

Such damage is unsightly but seldom fatal. See the healthy green part of each leaf? Use scissors to trim off the tissue-paper-like frozen tips [see how], cutting each leaf to a point. When you’re done, the damage will be barely noticeable. By summer new growth will have hidden those shorter, trimmed leaves. (Note: Such damage is similar to scorching caused by too much sun and heat, typical of desert climates, and by—believe it or not—wildfire.)

 

Cold Weather Care for Garden Succulents

What about an agave or other 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.

Areas of occasional, mild frosts (like inland Southern CA):

Watch the weather forecast, and if there’s a “frost advisory” for your area, before dark go outside and cover your tender succulents. Frost tends to happen after midnight, with temps getting colder toward dawn. 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. The succulents you have to worry about are those 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 live in the foothills NE of San Diego at 1,500 feet (Zone 9b). And yes, I’ve been outdoors in my pajamas and slippers at 11 pm after hearing the weather forecast on the late-night news, shivering as I throw sheets on vulnerable plants, while my husband holds a flashlight. If frost is predicted for a series of nights, I may leave the plants covered; otherwise, I remove the sheets the next morning. To make sure they won’t blow off, I secure them with clothes pins and rocks. Do NOT use plastic. It doesn’t allow the plants to breathe.

Frost and Succulents: What You Need to Know

Frost cloth protects jades and other vulnerable succulents in my garden. See the video. 

Why cold damages some succulents and not others

A lot has to do with where a particular kind of plant originated. Succulents, which store water in their leaves to survive drought, are mostly from dry, hot climates. But some are from dry, cold climates—and those are the ones that don’t freeze. See my article in the Wall Street Journal: Showy Succulents for Snowy Climates. Among the “hardies” are:

Frost and Succulents: What You Need to Know

Stonecrops (small-leaved sedums), like those above in a Colorado rock garden…

Frost and Succulents: What You Need to Know

sempervivums (hens-and-chicks, above) of which there are numerous species and cultivars; certain cacti, yuccas and agaves (like Agave utahensis, A. montana and A. parryi), and lewisias from the Pacific Northwest.

Related Info on This Site:

Overwintering

How to grow indoors

Cold Weather Care for Outdoor Succulents

Frost damage

 

Learn more in my books:

Designing with Succulents (2nd ed.):
— Cold-Climate Succulent Gardens, pp. 111-113
— Cultivating Succulents in Challenging Climates, pp. 143-148

Succulents Simplified:
— Protection from Frost, pp. 48-50
— Frost Damage, p. 72 and p. 77

I also recommend Hardy Succulents, by Gwen Kelaidis, illustrated by Saxon Holt:

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Cold weather care for outdoor succulents
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Cold Weather Care for Outdoor Succulents, By Region

Cold Weather Care for Outdoor Succulents, By Region

Should you be worried about your outdoor succulents in winter? It depends on where you live.

It’s all about frost. The temperature at which water freezes—32 degrees F—is the Great Divide. Above that, most succulents are fine. Below that, most are at risk. See “Frost and Succulents: What You Need to Know.

Hardiness Zone Map

The USDA Plant Hardiness Zone Map is a good basic guideline. However, it doesn’t take into account climate variables potentially harmful to succulents.

Regional Care for Succulents, An Overview

There’s very little of North America where every kind of succulent will grow outdoors year-round. The “banana belt” is the heavily populated California coast. Of course, you can grow any succulent anywhere if you’re able to replicate the conditions it likes, either in your home or in a greenhouse. But this article is about cultivating succulents outdoors, in the garden, during the most challenging season: winter.

If you live in…

Coastal CA from the Bay Area south: You don’t get frost (at lower elevations), and humidity and rainfall are minimal, so simply make sure your succulents get good drainage during occasional rainstorms.

Cold weather care for outdoor succulents

My garden is in Southern CA inland, in the foothills NE of San Diego at 1,500 feet (Zone 9b). A freak snowfall happened on New Year’s Day, 2017. When temps rose above freezing, I hosed off the snow. The Agave attenuata at left was damaged but recovered.

Central and Southern CA inland: Frosty nights tend to follow rainy weather, December through February. Like a citrus grower, I pay attention to “frost advisories for inland valleys.” When temps are predicted to drop below 32, I drape succulents with bed sheets or commercial frost cloth made of non-woven fabric[Learn more about how I protect my garden.]

Cold Weather Care for Garden Succulents

When a non-gardening friend noticed bedsheets draped over my plants, she asked if my dryer wasn’t working (!).

Areas of hard frost: You get temps below 32 degrees that last for hours, so it’s not adequate to merely cover your in-ground succulents or shelter potted succulents beneath eaves. Move them indoors or into a greenhouse. Depending on where you live, an inexpensive temporary shelter may be OK. [See “Four Ways to Overwinter Succulents” on this site.]

Northwest and Northeast: Protect and shelter your succulents indoors (perhaps in your basement) or in a climate-controlled greenhouse. [On this site, See “Cold-Hardy Succulents for Northern Climates” for exceptions; “How to Grow Succulents Indoors;” and “Winter Protection for Succulents: Products].

Desert Southwest: You get hard frosts, so protect and shelter tender succulents indoors or in a climate-controlled greenhouse. Those that do well for you include cacti, agaves, dasylirions, yuccas and other succulents specific to your region.

South: If you get frost, see above. But even if temps stay above freezing, you’ll still contend year-round with trying to grow arid-region plants in a wet, humid climate. Find out which succulents you can grow outdoors in Florida and other states too damp and humid for most succulents.

Related info on this site:
How to grow indoors
Overwintering

Frost and succulents Frost damage

Learn more in my books:

Designing with Succulents (2nd ed.):
— Cold-Climate Succulent Gardens, pp. 111-113
— Cultivating Succulents in Challenging Climates, pp. 143-148

Succulents Simplified:
— Protection from Frost, pp. 48-50
— Frost Damage, p. 72 and p. 77

I also recommend this excellent book: Hardy Succulents by Gwen Kelaidis, photos by Saxon Holt.Cold Weather Care for Garden Succulents