How to Overwinter Aeoniums: The Complete Winter Care Guide

Overwintering Aeoniums is undoubtedly one of the most important topics for any collector. While these succulents, native to the Canary Islands, appreciate the mild temperatures of the Mediterranean winter, they remain particularly sensitive to frost. Appropriate protection is therefore essential in most regions of France.

In this guide, Variegated Aeonium presents the different solutions to effectively protect your Aeoniums in winter , depending on your climate, available space and budget.

Are Aeoniums frost-resistant?

Unlike many succulents, Aeoniums are not hardy . Most species and cultivars cannot tolerate prolonged periods of freezing temperatures.

Under very specific conditions—perfectly dry substrate, low humidity, and very brief frosts—some varieties can tolerate slightly negative temperatures. However, this resistance remains limited and should never be considered a rule.

The main objective of wintering is therefore to keep the plants frost-free , while maintaining a bright, well-ventilated and relatively cool environment in order to respect their natural growth cycle.

Ideal wintering conditions

Aeoniums are winter-growing plants. Their development is optimal when temperatures are generally between 10 and 25 °C .

Contrary to popular belief, they appreciate:

excellent brightness;
good air circulation;
moderate rainfall when drainage is perfect;
Cool but above-freezing temperatures.

Whenever possible, it is therefore best to leave Aeoniums outdoors all winter, protecting them only from frost. Depending on your region, different solutions may be possible.

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1. The unheated greenhouse: the best solution in temperate regions

For most collectors, an unheated greenhouse offers the best compromise between effectiveness, simplicity, and running costs.

Without any heating system, it protects Aeoniums from winter rainfall, limits excessive moisture in the growing medium, and naturally benefits from the greenhouse effect created by sunlight.

This solution is particularly well suited to regions where temperatures only occasionally fall below 0°C (32°F).

Advantages

excellent light levels;
protection from bad weather;
a growing medium that remains drier;
a natural greenhouse effect during the day.

Points to Watch

A poorly ventilated greenhouse can quickly become an environment favorable to the development of fungi, mold, and fungal diseases.

It is therefore recommended to:

regularly open the door and roof vents;
install one or more greenhouse fans;
use a timer to provide automatic daily ventilation.

Polycarbonate greenhouses, glass greenhouses, and horticultural tunnels can all provide excellent results. In windy regions, make sure the structure is securely anchored and protected from prevailing winds. Greenhouse anchoring systems can provide additional stability when the structure is exposed to strong winds.

2. A Heated Greenhouse: Only to Keep Plants Frost-Free

Where winters are more severe, a heated greenhouse can be an excellent solution.

The goal, however, is not to create a tropical climate. Aeoniums simply do not need one.

It is usually sufficient to keep the temperature slightly above 0°C (32°F) to prevent any risk of frost damage.

For this purpose, the setup generally includes:

a heater designed for greenhouse use;
a thermostat with a temperature probe that can automatically switch the heater on when needed;
good ventilation.

The equipment I use: personally, I chose an Inkbird smart thermostat. It automatically controls the heater according to the temperature measured by its probe and allows me to monitor the greenhouse from a smartphone via Wi-Fi. This remote monitoring is extremely convenient and makes it possible to react quickly in the event of a malfunction or an abnormal drop in temperature.

In an unheated greenhouse, or simply as an independent monitoring system, a smart thermometer-hygrometer with alerts can also be useful. It does not control any equipment, but it allows you to monitor temperature and humidity remotely and receive an alert when a critical threshold is reached. However, the greenhouse must be within range of your Wi-Fi network.

Electrical safety: a greenhouse is a humid environment. Extension cords, outlets, plugs, and electrical connections must be suitable for these conditions, protected against water splashes, and connected to an electrical installation equipped with appropriate residual-current protection. An outdoor power strip with integrated residual-current protection can provide additional protection, but it is not a substitute for a properly installed and compliant electrical system.

3. Overwintering Aeoniums Outdoors Under Protection

When installing a greenhouse is not an option, it is entirely possible to protect Aeoniums effectively while keeping them outdoors.

This method is economical and particularly suitable for regions that experience only occasional frosts.

A Heavy-Duty Greenhouse Cover

When frost is forecast, a 200-micron horticultural greenhouse cover (approximately 200 g/m²) provides an excellent first layer of protection.

Placed above the plants, it creates a genuine greenhouse effect during the first hours of the morning, helping to significantly reduce frost damage.

An east-facing position is particularly beneficial, as the morning sun quickly warms the air beneath the cover.

Adding Horticultural Bubble Wrap

For additional insulation, UV-treated horticultural bubble wrap can be installed beneath the outer cover. Horticultural-grade bubble wrap withstands prolonged exposure to sunlight better than ordinary packaging bubble wrap.

The trapped air bubbles naturally improve thermal insulation and can help maintain temperatures several degrees warmer during cold nights.

A Simple and Inexpensive Structure

A few hoops suited to the width of the protective cover, or bent electrical conduit, are generally sufficient to create a lightweight structure that prevents the cover from resting directly on the plants.

Maintaining this gap is important to prevent cold from being transferred directly to the rosettes through contact.

Heating Cable: A Highly Effective Solution

In regions where frosts remain moderate, adding a heating cable suitable for this purpose can be a particularly effective solution.

The model I use has an output of approximately 30 W per meter, which is sufficient to raise the temperature slightly beneath the protective cover.

When connected to a thermostat with a temperature probe, it can switch on automatically as the temperature approaches 0°C (32°F) and turn off again once the risk of frost has passed. A standard timer cannot respond to changes in temperature and therefore does not provide the same protection.

Just a few additional degrees are often enough to protect an entire collection.

Adding Frost Cloth for Extra Protection

When lower temperatures are forecast, adding one or more layers of frost cloth is recommended.

In colder regions, several overlapping layers provide significantly greater protection.

However, if severe or prolonged frost is forecast, it is preferable to move the plants temporarily indoors rather than take unnecessary risks.

Choosing the Right Frost Cloth

Frost cloth is made from nonwoven polypropylene, allowing air and some moisture to pass through while helping to reduce heat loss.

Its effectiveness depends mainly on its fabric weight.

As a general guide:

P17: lightweight forcing fleece offering very limited protection (approximately 1–2°C / 2–4°F);
P30: the most commonly used grade, providing approximately 2–4°C / 4–7°F of additional protection;
P50 to P100: heavier-duty protection for colder climates.

It is often preferable to use several layers of P30 frost cloth rather than a single very thick layer, as this allows more light to reach the plants.

Also remember to insulate the pots from the ground using blocks, stands, or other supports to reduce the transfer of cold from the ground.

4. Overwintering Aeoniums Indoors

When climatic conditions become too extreme, it is perfectly possible to overwinter Aeoniums indoors.

For a short period of just a few days, a bright room, a frost-free garage, or a cool conservatory can work perfectly well.

However, if the plants need to remain indoors for several weeks, a few precautions are essential.

The first concerns light. Since Aeoniums require high light levels during their active growth period, grow lights suited to the size of the growing area quickly become essential to prevent etiolation.

The second important factor is ventilation. Stagnant air encourages the development of diseases and creates favorable conditions for many pests, particularly mealybugs and aphids.

Using small fans programmed to run for a few hours each day can considerably improve indoor growing conditions.

Variegated Aeonium also features comprehensive guides on grow lights for Aeoniums and mealybug control, two essential topics for successfully overwintering Aeoniums indoors.

In Summary

There is no single universal method for overwintering Aeoniums. The best solution depends primarily on your local climate and the facilities available to you.

In most regions of France, a properly ventilated unheated greenhouse remains the most effective solution. Colder regions may require supplemental heating controlled by a thermostat, while milder climates will often allow Aeoniums to overwinter outdoors under a protective cover, with additional frost cloth or a heating cable when necessary.

Whatever method you choose, three rules remain essential: protect your Aeoniums from frost, keep the growing medium well drained, and maintain excellent air circulation. These are the best ways to ensure that your Aeoniums emerge in spring healthy, well rested, and ready to resume active growth.

Checklist for Successful Overwintering

You do not need to own all of this equipment. What you need depends on your climate and the type of protection you use. Follow this order: monitor first, insulate, add heat only when necessary, and finally make sure the electrical installation is safe.

1. Monitor the Temperature Before Taking Action

Smart thermometer-hygrometer with alerts: the most comprehensive solution for remotely monitoring temperature and humidity and receiving alerts when a critical threshold is reached.
Budget min/max thermometer: no app or Wi-Fi required; it records the lowest temperature reached during the night.

2. Protect Plants from Cold and Excess Moisture

P30 frost cloth or heavier: place it around the plants when frost is forecast. Several layers can provide additional protection.
200-micron horticultural greenhouse cover and horticultural bubble wrap: the greenhouse cover mainly protects against the elements, while the bubble wrap provides additional thermal insulation.

3. Add Heat Only When Passive Protection Is No Longer Enough

Inkbird smart thermostat used by HOLDWIG: automatically switches the heater on according to the temperature measured by its probe and also allows remote monitoring.
Greenhouse heater suitable for humid environments: choose the appropriate output for the size of your greenhouse and use it only to keep the plants frost-free.
Heating cable combined with a thermostat and temperature probe: a compact, localized solution when only a few additional degrees of protection are required.

4. Make Sure the Electrical Installation Is Safe

Safe outdoor electrical equipment: use outlets, plugs, and connections designed to withstand water splashes, together with appropriate residual-current protection. These devices provide additional protection but do not replace a properly installed and compliant electrical system.