When we think of cactus, the first thing that comes to mind is an image of a vast desert, with an intense and bright sun, and a lonely Saguaro enduring the inclement heat.
Something like that…
However, its great variety and distribution throughout the continent, mean that it is not exclusive to this environment, and that in many places it experiences the classic seasonal changes of the hemispheres. Not only that, their popularity makes us now love to cultivate them and keep them company at home, away from their surroundings, so the question arises… can cactus survive winter?
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- 1 How do cactuses survive winter?
- 2 What temperature is too cold for cactus?
- 3 Caring for outdoor cactus in winter
- 4 List of Cold Hardy Cacti
- 5 How to protect cactus from frost?
How do cactuses survive winter?
As survival plants par excellence, cacti have developed mechanisms that allow them to withstand high temperatures and low humidity conditions, such as water retention and others that we have already described on other occasions.
Now, to withstand the cold they work totally different. The main thing is that they stop absorbing water or reduce its absorption to a minimum, in fact, many species dry out and harden to avoid losing large amounts of water. Low temperatures reduce humidity in the environment and this could cause more water to come out of the cactus, as it dries and hardens, the cactus seals the water outlets and creates a shell that protects the interior.
This process is the equivalent of hibernation of mammals, it is a process of lethargy or voluntary rest that allows them to face icy conditions.
What temperature is too cold for cactus?
Bear in mind that not all species can withstand subzero temperatures for a whole winter season, although there are those that can withstand up to -25 °C, commonly varieties that grow very north or very south of the American continent.
How much cold they tolerate will depend on many variables, such as the species of cactus, type of soil where it is planted, if there are frequent rains or snow in winter or only dry and very low temperatures.
As cacti reduce or stop water absorption during this time, there is a great risk of root damage in moist soils. The accumulation of water can cause the roots to rot or freeze due to low temperatures leading to the death of the plant.
Cacti do not need, in fact, they should not be in contact with water in the winter period. Many can come into contact with snow without serious consequences, as long as there is no moisture on the ground.
Caring for outdoor cactus in winter
- FIRST, it is essential to consult and investigate what temperatures our Cactus species can withstand, otherwise we risk them dying due to environmental conditions.
- Maintain a substrate in the pots that allows constant drainage and no accumulation of water during the winter. What if you have them planted in pots? By late fall the task will be to let the soil where the cacti are dry to prevent damage in the winter.
- Many species will dry out and appear dead. We must be patient and wait a couple of weeks after winter to resume watering. It’s preferable to increase irrigation gradually.
- If you have cacti and other succulents in greenhouses, you have to be more careful. Being in a controlled environment at this time, the sun can do a lot of damage—remember that they are not receiving hydration.
- If your cacti withstand the cold of temperate zones well but not snow, or it rains in your region in the winter, you can cover the pots or the ground with waterproof materials or tarps. In this way we avoid direct contact, and reduce the risk. Don’t worry about covering them for days—they’ll still be there, and you’re doing them a favor. Just check regularly to make sure it’s not damp under the covers.
- Last but not least: DO NOT TRANSPLANT IN WINTER. Being in a state of lethargy they will not be able to adapt to the new terrain. It’s preferable to transplant no later than mid-autumn or spring.
If you’re planning to bring your cacti indoors during winter, make sure they continue to receive sufficient light. To do that, you can use these grow lights for cacti.
List of Cold Hardy Cacti
Do you live in a climate where there is usually frost but you really want to have some cold resistant cacti? If so, you are in luck, because even though they are plants that are used to living in hot climates, the reality is that in deserts at night the temperature drops a lot and quickly, so everything that lives in them must know how to adapt to these conditions.
So to have an idyllic garden or patio in areas where the winter produces some frosts it is also possible to have some cacti. Here you have our selection.
1,000 Types of Cactuses with Pictures
The Ferocactus, are globular plants with very long spines (about 5-7 cm), up to 1cm wide and curved. They live in the deserts of California and Baja California, some areas of Arizona, southern Nevada and Mexico, so in general they can tolerate frosts down to -4 ºC well.
Since most of this genus withstands light frosts, it is usually recommended as a whole, but the truth is that some species endure much longer than others. Also keep in mind that if they are not kept completely dry during frost, they are very likely to rot. This is the approximate cold resistance of the most common species:
- Ferocactus gracilis (-2 ºC)
- Ferocactus glaucescens (It is not recommended to expose it to frost, but it can hold up to -2 ºC)
- Ferocactus pilosus (It is not recommended to expose it to frost, but it can hold up to -3 ºC)
- Ferocactus emoryi (-6 ºC)
- Ferocactus rectispinus (-3 ºC)
- Ferocactus robustus (-6 ºC)
- Ferocactus macrodiscus (It is not recommended to expose it to frost, but it can hold up to -2 ºC)
- Ferocactus wislizeni (-6 ºC)
Echinopsis are cacti that can be globular or columnar. Their spines are more or less long, between 1 and 3 cm depending on the species. And they have some flowers… not beautiful, like the following, as you can see in the image. Living in Argentina, Chile, Bolivia, Peru, Brazil, Ecuador, Paraguay and Uruguay, within this genus we can find interesting plants to have in climates with average frosts down to -8 ºC. These are cacti that you can always buy and trust to survive the winters, so they are worth acknowledging. These are some of the most common:
- Echinopsis subdenudata (-7 ºC)
- Echinopsis oxygona (-6 ºC)
- Echinopsis leucantha (-12 ºC)
- Echinopsis chamaecereus (-8 ºC)
- Echinopsis (Lobivia) cinnabarina (-12 ºC)
Today, although it is an accepted genus, most of its species have moved to the genus Echinopsis. Here we are going to talk about both the columnar Echinopsis that previously belonged to this genus, and those that are now considered Trichocereus. The entire Trichocereeae tribe is under review and species are being changed from one genera to another. In the hobby, columnar Echinopsis is often called Trichocereus and the old names are preferred, since the new ones change as soon as you learn them.
They inhabit western South America, from Ecuador to central Chile, mainly in the Andes. They look similar to Echinopsis, with the same flowers and fruits, but tend to be finer. If we include all columnar Echinopsis, the differences are that they are much taller and less branched than the rest of Echinopsis, and they usually have fibers that come out of the areoles from a certain height to protect them from the sun. Since they tend to grow at high altitudes, they are highly resistant to cold, but they take heat worse and need more water than other cacti. Besides that, they are one of the fastest growing cacti.
- Echinopsis atacamensis (formerly Trichocereus pasacana) (-12 ºC)
- Trichocereus pachanoi (According to Plants of the World Online, today it must be considered a subspecies of Trichocereus macrogonus, although years ago it was renamed Echinopsis pachanoi) (-12 ºC)
- Echinopsis lageniformis (formerly Trichocereus bridgesii) (-10 ºC)
The Oreocereus are generally columnar cacti that reach about 3 m in height. They are very decorative, as their stems are covered with fibers as a consequence of the climate of the Andes, which is where they originate.
Almost all species can withstand frosts down to -15 ºC, but only if they are kept completely dry. If they are exposed to strong frosts with the substrate wet, they rot very easily. The most common, along with the temperatures that can withstand with the wet substrate are:
- Oreocereus trollii (-5 ºC)
- Oreocereus celsianus (-10 ºC)
In the genus Cleistocactus there are many cacti that withstand temperatures close to -5 ºC, but the most used is Cleistocactus strausii. This species is undoubtedly the cold-resistant cactus that is most sought after in cold and humid climates. It withstands temperatures below -10 ºC, even on a wet substrate.
It is a columnar cactus up to 3 m high with very thin stems (rarely more than 10 cm thick), completely covered with white fibers and small yellowish spines up to 2 cm. It grows moderately fast and produces a large number of offsets, so it quickly acquires a good size. Its flowers are tubular and red, not very large, and never fully open.
They are very typical cacti, but also curious, forming flattened stems that lose their apex after reaching their size. Many also have typical spines, tiny spines (called glochids) that detach on contact and cause irritation. They are one of the few cacti with leaves, although they only have them while the stems are growing. Some species grow to be large trees and others barely rise 10 cm from the ground. The fruit of some species is consumed (mainly that of Opuntia ficus-indica) and is called prickly pear in parts of Latin America.
The most resistant to cold can withstand temperatures below -40 ºC, but the most cultivated ones have a hard time with about -10 ºC. It must be taken into account that it is a huge genus, with species distributed throughout the Americas, so its resistance to cold varies greatly. These are the most common:
- Opuntia ficus-indica (-6 ºC)
- Opuntia microdasys (-5 ºC)
- Opuntia macrocentra (-12 ºC)
- Opuntia monacantha (-3 ºC)
- Opuntia polyacantha (-15 to -45 ºC, depending on the clone)
Like Opuntia, they grow in segments, but in this case cylindrical. Some species only lose the apex on the lateral branches, having continuous growth on the main stem. Some make seedlings up to 3 or 4 meters high, while others do not exceed half a meter. They are one of the fastest growing cacti and usually have large harpoon-shaped spines (up to about 5 cm) with which they are stuck in the animals to transport them to another place.
It is interesting to know that they are very resistant to cold, although because they inhabit from central North America to southern Mexico, going down the eastern islands to northern South America, their resistance to cold varies a lot. Among those are:
- Cylindropuntia fulgida (-10 ºC)
- Cylindropuntia tunicata (-20 ºC)
- Cylindropuntia rosea (-15 ºC)
- Cylindropuntia imbricata (-28 ºC)
- Cylindropuntia spinosior (-20 ºC)
This genus is made up of small but very striking cacti, both for their large brightly-colored flowers and for their shape or coloring of the thorns. There are numerous species and their range covers almost the entire west coast and central United States and much of Mexico. That is why here we find some of the most cold-resistant medium-sized cacti. However, those that are usually commercialized are native to Mexico and therefore not very resistant. Even so, it is one of the genera that are a safe bet if your temperatures do not drop below -5 ºC. The most common and the most resistant are:
- Echinocereus rigidissimus (-12 ºC)
- Echinocereus pentalophus (-5 ºC)
- Echinocereus subinermis (-2 ºC)
- Echinocereus triglochidiatus (-25 ºC)
- Echinocereus dasyacanthus (-10 ºC)
- Echinocereus reichenbachii ( -30ºC )
- Echinocereus viridiflorus ( -20ºC)
These are small cacti that inhabit from Canada to Mexico, passing through the entire central United States. As you can imagine, coming from Canada, we find species that are the most cold-resistant cacti. They look similar to Mammillaria, but with larger flowers. They are usually completely covered with small thorns that prevent snow from reaching the stem. It is not difficult to see them for sale, but they are the typical plants that we overlook. The most resistant to cold are:
- Escobaria vivipara (-15 to -45 ºC, depending on the place of origin)
- Escobaria missouriensis (-35 ºC)
So, you just have to choose the one you like the most to enjoy a ‘piece’ of desert in your home.
How to protect cactus from frost?
To protect against excessive moisture due to snow and rain, give frost-resistant cacti outdoors a rain-protected location under a canopy. Alternatively, a simple frame made of posts and transparent greenhouse film acts as a rain canopy.
Read more: 5 Easy Ways How to Protect Cactus from Frost