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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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How to Grow Succulents Indoors

If you’re wondering how to grow succulents indoors, basically you need to outfit a basement, sun room, spare room or alcove with tables and shelves that can withstand moisture, plus lights and a fan that run on timers. Fortunately succulents need very little water. Dribble a little at the base of each plant every three weeks or so, enough to hydrate the roots but not so much it puddles on the floor. Don’t fertilize succulents when they’re dormant (growth slows to a standstill, usually in winter).

Move potted succulents indoors when temperatures drop into the 30s. Clean the pots’ exteriors and check for pests. Keep them above 32 degrees F but not higher than 60 (cold is necessary for flowering later on). Keep a fan running to enhance air circulation, and a dehumidifier if the air is moist.

Place your succulents near a window. Maximum sun exposure is on the south and west sides of your house. The farther north you live in North America, east will provide bright light, but not enough for crassulas, echeverias and aloes to maintain their red hues.

Don’t set plants near heaters or furnace vents. They’ll cause the soil to dry out and your plants to desiccate.

Install grow lights. Situate indoor succulents beneath lights that stay on six hours daily. Fluorescent is fine and economical. Experts in growing succulents in gray-sky climates recommend T-5 grow lights. If your plants stretch toward light (or flatten their rosettes to expose more of their surface area), add more lights or move the plants closer to the ones you have.

Agrobrite FLT44 T5 Fluorescent Grow Light System, 4 Feet, 4 Tubes, about $120 on Amazon.

 

No room? Go vertical. Create a “light island.” There are shelving units designed for indoor plants. Each shelf has a waterproof tray, and each unit is lit by two T5 bulbs. The lights, on timers, stay on from 7 am to 7 pm daily. Shown below is arguably the ultimate indoor plant-shelf unit. Made of lightweight, powder-coated aluminum, it has adjustable lights with energy-efficient, full-spectrum bulbs; plastic drip trays; and wheels for easy positioning. Three shelves provide 18 square feet of growing space. From Gardener’s Supply Co.; about $600. 

Get a timer which automatically turns the lights on at, say, 7 a.m. and off eight hours later. I like this one, below, because it has multiple outlets:  Titan Apollo 14, about $26. 

Watch the temperature. If it falls below freezing (32 degrees F) many succulents may show long-term damage (or die). This indoor thermometer is digital and also has a humidity gauge. But what I love about it is that it keeps daily high and low temps for 24 hours!

AcuRite 00613 Humidity Monitor with Indoor Thermometer, Digital Hygrometer and Humidity Gauge Indicator, about $12 on Amazon.

Watch for pests. Succulents in cramped conditions are at risk of mealy bugs, spider mites and other pests. At the first sign of infestation, spray with 70% Isopropyl alcohol. Isolate infested plants so pests don’t spread, and clean the surrounding area.

Related info on this site: Overwintering

 

How to keep succulents happy


 

 

Succulents and Too Much Rain, A French Solution

Want to protect your succulents from too much rain? Here’s how the Jardin Zoologique Tropical in southeastern France keeps their succulents from becoming waterlogged during seasonal rainstorms. Corrugated fiberglass panels atop metal bars tent the plants so excess rain doesn’t soak the soil.

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The structures are tall enough to allow good air circulation, and the panels are translucent, enabling maximum sunlight to reach the plants. The covers, which have a horizontal metal rod atop them so wind can’t lift them, also protect tender succulents from frost.

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Notice, too, that the plants grow in rocky, elevated, sloping soil, so water drains away from the roots.

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You might do something similar in your own garden with a patio umbrella secured in a concrete base. But keep in mind that the water has to go somewhere. The French garden’s panels channel rain onto the gravel roadway nearby.

Btw, this public garden, located near the village of La Londe-les-Maures, is deservedly proud of its succulent collection. Here’s a description from the website, courtesy of Google Translate. The common names of the plants are charming.

Our plant collection is rich in many varieties of succulent plants: agaves, aloes and euphorbias. Every season their blooms transform the gardens. We regularly introduce little-known species and observe them for their ornamental potential. Perhaps the best known are cacti native to the Americas. We grow several species hardy in our climate. Some are globular, like the famous “mother-cushions,” others are elongated, cylindrical and commonly called “candle cactus.” Visitors easily identify the “prickly pear,” also called “Mickey Mouse ears” or “cactus rackets.”

(Photos used with permission.)

Related info

On this site:

How to Water Succulents These fleshy-leaved plants from hot, dry regions are designed to live off water stored in their leaves and tissues in order to survive periods without rainfall. But this doesn’t mean you shouldn’t water them at all…[Continue reading]

Prepare Your Succulents for Rainstorms  Succulents, which come from arid climates, may rot. Stems or trunks turn squishy and collapse. It may be possible to… [Continue reading]

Learn about pumice. No other soil amendment is as widely used by succulent growers and collectors as pumice (crushed lava rock). Here’s why…[Continue reading]

Oh, No, My Succulents Froze!  Will succulents recover from frost damage? It depends. Here’s how frost-tender succulents looked before temps dropped into the mid-20s F, and after…[Continue reading]

Caring for Your Succulent Garden After Rainstorms, Checklist  Rain at last! Could the California drought finally be over? Well, no. It’ll take hundreds of years for underground aquifers…[Continue reading]

Winter Protection for Succulents: Products  Soggy soil, dim light, high humidity and freezing temperatures can be death to succulents native to warm, arid climates. These items will help you get your succulents through cold, wet North American winters…[Continue reading]

On My YouTube channel: 

Why Succulents Rot and How to Prevent It

Why Rain is Good for Potted Succulents

Post-Rain Must-Do’s for Succulent Gardens

 

Books by Debra Lee Baldwin

Snail on Succulent
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Prepare Your Succulents for Rainstorms

How to Prepare Your Succulents
for Rainstorms

While gardening between El Niño storms, I inadvertently threw a snail through the open window of a passing pickup truck. I realized this because, unlike previously tossed mollusks, I didn’t hear the sound of shell hitting asphalt. If the driver had stopped, I would’ve apologized and explained that it wasn’t personal—at least not where he was concerned.

Snail on Succulent

The snail photo is from the first edition of Designing with Succulents, which means the snail would be 10+ years old had it lived. Of course it didn’t.

 

Snails reproduce in abundance in wet weather and unless stopped chew unsightly holes in plants. This is truly a shame because succulents keep their leaves a long time. An environmentally friendly bait is Sluggo, but it’s expensive, as are decollate (predator) snails—which in any case are not legal in every California county. The most expedient method, squashing underfoot, leaves a sticky residue on shoes. So I step on a leaf instead, which is one reason I grow nasturtiums. Set a snail on the ground, place a nasturtium leaf atop it, and step on it. If there’s no crunch, find harder ground. But not your patio; snails stain.

And then there’s rot

An even bigger concern during El Niño is that succulents, which come from arid climates, may rot. Stems or trunks turn squishy and collapse. It may be possible to take cuttings from healthy top growth and restart the plants—as I did that rainy winter with aeoniums. Fortunately, the rest of my succulents came through fine, despite double normal rainfall. After all, it’s not water that causes roots to rot, but drowning from lack of oxygen (plus microbes). Consider: Agave attenuata, crassulas, yuccas and other succulents thrive in Hilo, Hawaii, shown below, where precipitation averages 200+ inches a year. Rain bathes the roots continually, but they stay aerated and healthy because the soil is fast-draining lava rock.

 

Succulents in Hilo, Hawaii

 

If succulents occupy low-lying areas of your garden where rain tends to puddle, and you don’t want to move the plants to higher ground, use a patio umbrella to keep them from being soaked. Channel run-off with rocks, sandbags or trenches; and top-dress soggy soil with pumice to absorb standing water.

 

 

 

 

 

 

 

 

 

Perhaps the best soil amendment for succulents is pumice, a lightweight crushed volcanic rock that aerates the growing medium and absorbs excess moisture. I mix pumice half-and-half with bagged potting soil for containers; and with equal parts compost and garden soil or decomposed granite for in-ground beds. [Learn more about pumice.]

Related info

On this site:

How to Water Succulents These fleshy-leaved plants from hot, dry regions are designed to live off water stored in their leaves and tissues in order to survive periods without rainfall. But this doesn’t mean you shouldn’t water them at all…[Continue reading]

Learn about pumice. No other soil amendment is as widely used by succulent growers and collectors as pumice (crushed lava rock). Here’s why…[Continue reading]

Succulents and Too Much Rain, A French Solution Want to protect your succulents from too much rain? Here’s how the Jardin Zoologique Tropical in southeastern France…[Continue reading]

Oh, No, My Succulents Froze!  Will succulents recover from frost damage? It depends. Here’s how frost-tender succulents looked before temps dropped into the mid-20s F, and after…[Continue reading]

Caring for Your Succulent Garden After Rainstorms, Checklist  Rain at last! Could the California drought finally be over? Well, no. It’ll take hundreds of years for underground aquifers…[Continue reading]

Winter Protection for Succulents: Products  Soggy soil, dim light, high humidity and freezing temperatures can be death to succulents native to warm, arid climates. These items will help you get your succulents through cold, wet North American winters…[Continue reading]

On My YouTube channel: 

Why Succulents Rot and How to Prevent It

Why Rain is Good for Potted Succulents

Post-Rain Must-Do’s for Succulent Gardens

 

Books by Debra Lee Baldwin