Succulents are mostly exceptionally hardy plants but, unfortunately, the majority is not frost tolerant. Depending on the climate and the amount of frosty days, succulents will need varying degrees of protection to make it through the winter.
Frost will form on surface of plants when their temperature is lower than the dew-point temperature of the air around them and below the freezing point of 0C/32F. Frost is especially dangerous for succulents as they are filled with water. Essentially, this water will freeze inside them causing the plant to collapse.
You will notice that frost tolerant plants and succulents will have thin leaves (thin needle leaf trees, conifers or sempervivum). The very thing that makes succulents so attractive (swollen, chunky leaves) is also the reason they are so susceptible to dying when frost hits in winter.
Most succulents will survive unprotected in temperatures to about 1C/33F. It is only when the mercury dips below the freezing point that succulents will start freezing.
However, there are ways of helping succulents stay alive during the winter months.
How to keep succulents alive in winter?
Frost hardy succulents
1. Frost Cloth
In moderate frosts to about -5C (24F) frost cloth will help protect succulents from suffering frost burn. Most succulents will die if exposed to these kinds of temperatures without any protection whatsoever.
Frost cloth can be put over garden succulents and is made from lightweight, breathable material that will allow air to get in but will stop frost settling on your plants. It will also allow water and sun’s rays in.
Frost cloth will need to be weighed down around the succulents to keep the heat it and frost out. It can be draped over plants or over a structure to create a mini greenhouse. Whichever way you decide to do it, there should be minimal to no gaps for maximum effect.
Pegs, bricks or rocks can be used to secure the frost cloth, so it doesn’t blow away or let frost in.
Although, frost cloth will not protect succulents in the deep winter frosts of over -5C, in cold climates, it buys time. The less time succulents have to stay indoors during the worst of winter, the better.
Indoors many succulents will deteriorate fast as there is just not enough light. Succulent growing lights may help (better quality the lights, better they will grow), but they are generally best of outdoors.
If your area does not experience frosts over -5C/24F than you’re in luck as succulents will be able to live outdoors even during winter with the help of this handy tool.
One incredibly important thing to remember with a frost cloth is to remove it when the temperatures during the day rise. On a sunny day, the heat trapped under the frost cloth can effectively cook succulents.
Only put frost cloth over succulents when frost is expected and remove once it has passed.
A simple plastic greenhouse will protect succulents in mild frost to about -5C/24F, just like the frost cloth. However, additional layers of protection can be added to the greenhouse in order to increase the temperature inside.
Extra layer of frost cloth, sheets or even a bubble wrap will push the threshold of resistance to worsening outside frost.
Panel polycarbonate greenhouses will have higher protection qualities against winter frosts and snow but they have limitations as well. Again, bubble wrap (horticultural grades are available) or frost cloth can increase the temperature inside the greenhouse.
There should also be no gaps for cold air to get in and warm air to escape. Any gaps will need to be blocked out.
Greenhouses can also have heating installed, though this can be quite expensive. A heated greenhouse should protect against some serious winter weather.
Greenhouse heating can come from renewable sources, electric, hot water, wood-fired, gas or oil. For a small hobby grower, greenhouse heating may just not be viable. But if you have a serious succulent collection or run a small business selling succulents, a heating system can be invaluable in cold climates.
Gas greenhouse heaters are the least expensive option, followed by electric, though a safe electric point would need to be installed inside the greenhouse.
Keeping succulents alive in winter by bringing them indoors may seem like a no-brainer. But there is a catch. While inside the house is frost free, it is also light deficient.
The great majority of succulents do not like being grown indoors even if it’s on a windowsill. Over four hours of sunlight is usually needed to keep succulents growing compact.
Indoors succulents are likely to start stretching and turning towards the brightest light. The overall appearance will be ‘leggy’. Many rosette shape succulents can even star growing from the middle and completely lose their shape.
If a sunroom or a large glass wall is also part of the house then the plants will be quite happy having a vacation inside, though the majority of houses are unlikely to have a luxury of a sunroom.
Apart from keeping succulents on the brightest, sunniest windowsill during winter it may help to get plant growing lights. Some of these lights are better than others.
While cheap plant growing lights may help to an extent many succulents are still likely to lose their shape in 2 or so months. Professional plant growing lights are available, but they usually come at a price.
Sometimes it comes down to experimenting as standard plant growing lights may just get some succulents over the worst of winter. Not all succulents are created equal and some may tolerate being kept indoors for a month or two better than others.
It is important that they do spend as little time as possible indoors and as soon as danger of frost passes, they should be popped back outside in the sun.
4. Frost hardy succulents
Some succulents are frost hardy to over -10C (14F). These are namely Sempervivum species. Plants in this genus will tolerate some pretty harsh frost and a blanket of snow.
Growing Sempervivum in cold climate gardens kind of makes sense as there is no extra care required. Plants in the ground will by much more hardy than those in pots. The ground will have more of an insulating effect. Pots can well and truly freeze over which can stress the roots and, therefore, the plant to the point of death.
Other plants that will tolerate mild frosts are small leaf Sedum, Orostachys, Agave or Yucca. These succulents should survive winter frosts even better when planted in the ground.
If it’s getting too nippy outside a frost cloth can be popped over just in case. Mulching will also help protect the root system and may prevent soil from freezing.
If you’re worried about your frost hardy succulents the option of frost cloth is always there. Once the worst of winter is over, it can be removed.
To conclude growing succulents in cold climates can be a real bummer as the majority is not frost hardy. Frost cloth, greenhouses and houses can all help with keeping precious plants alive while winter rages outside. All options have their advantages and disadvantages, but even in very sold climates it should not be too hard to overwinter succulents during winter.