The group of succulents includes hundreds of plant families with their species, the thorn-reinforced cacti are probably the most well-known. It also includes thick leaf plants, midday flowers, pursley and other families. What they have in common is the ability to store water in their organs and thus survive long dry periods. Many succulents come from subtropical regions, some are hardy and insensitive to frost due to adaptation or breeding. Today’s article is about how cold can succulents tolerate and we will present the most beautiful winter hardy species here.
- Winter Hardy Succulents
- How Cold can Succulents Tolerate?
Winter Hardy Succulents
What are hardy succulents?
Succulents are available in many forms and colours, after all, the term sometimes combines very different and not closely related plant families and species. Most of them are not hardy and are best wintered in cold house, i.e. frost-free, but bright and cold. During the summer months, these specimens feel very comfortable in a sunny place in the garden or on the balcony. Winter hardy succulents, on the other hand, have developed a certain degree of resistance to cold and frost. In some cases, they can withstand temperatures of well below zero degrees Celsius and can therefore easily hibernate outdoors.
Why are some succulents hardy?
A special feature of their metabolism makes the hardy succulents insensitive to frost and wintry cold. To get it going, do not water them from the beginning of September until the beginning of March (and, if they are outdoors, do not let them irrigate). As a result, the plant begins to convert existing residual water into sugar. This reduces the water content in the plant cells, which in turn benefits the winter hardness: water finally freezes during frost and destroys the plant cells. But if none is left, even the strongest frost of the plant can no longer do anything.
Protecting hardy succulents from moisture
For the same reason, the hardy succulents should be protected from moisture. Therefore, make sure that you use:
- wind-protected, southern hillside location for planted succulents
- a well-drained substrate and a good drainage for succulents cultivated in the pot
- a wet protection by gravel, bimstone or similar
- a rain protection
If the drainage works well, the plants can withstand dry frost very well. This is especially true for many desert dwellers, who are often used to extreme temperature changes anyway. Snow usually doesn’t do any harm either, but instead serves as a kind of thermal blanket. However, depending on the amount of snow, it can become problematic during spring melt as a result of the rising water pressure: Here you should remove the snow before it thaws to avoid waterlogging.
How Cold can Succulents Tolerate?
Below are the 5 most beautiful winter hardy species and how low a temperature they can survive.
Ice Plant / Midday Flower (Delosperma)
Most of the midday flowers are not hardy, after all they come from the warm regions of South Africa and other African countries. However, some low-growing species are sufficiently frost hardy to overwinter outside in the rock garden, for example. As a rule, tall midday flowers are not hardy. Examples of particularly robust and beautifully blooming varieties in summer are:
- ‘Red Mountain Flame’: without rain protection, hardy to approx. minus 20°C
- ‘Indian Summer’: without rain protection, hardy to around minus 16 to minus 20°C
- ‘Fire Spinner’: without rain protection, winter hardy to approx. minus 20°C
- ‘African Queen’: with rain protection hardy to approx. minus 21°C
- ‘Gold Nugget’: without rain protection, winter hardy to approx. minus 20°C
The sedum plant, which is very popular in many gardens, is also known as ‘stonecrop’. There are around 300 different species, most of which are evergreen. Some species shed their leaves before winter and sprout again in spring. Typical of this succulent plant genus are not only their great variety of shapes and colors, but also their resistance to cold.
A common species is the mat-forming Sedum acre. This yellow blooming stonecrop is perfectly adapted to winter (USDA hardiness zones 4 to 9) and does not need winter protection.
- ‘Minor’: forms dense cushions up to 2.5 centimeters high
- ‘Aureum’: strong yellow cushions of flowers
- ‘Yellow Queen’: dense, bright yellow cushions of flowers
Sedum album, the ‘white stonecrop’, is also widespread in America and Europe. This loose lawn-forming species with lush white flowers is also absolutely hardy (USDA hardiness zones 3 to 8).
- ‘Bella d’Inferno’: pretty light yellow shoot tips
- ‘Coral Carpet’: forms bronze-red colored carpets with white flowers
- ‘Goldfinger’: forms yellowish, dense cushions
- ‘Hillbrandii’: brown-red cushions with a particularly large number of white flowers
- ‘Beacon’: forms very dense cushions, bright yellow-colored shoot tips
Hens and Chicks / Houseleek (Sempervivum)
Houseleek is a native thick-leaf plant, as it has sometimes bizarre leaf shapes and colorful flowers. Frosty temperatures do not affect the hardy plant (USA hardiness zones 3 to 8), but it must be in a location that is absolutely protected from moisture. Around 7,000 different varieties of around 40 species are currently known. The following species are particularly hardy:
- Real houseleek (Sempervivum tectorum): particularly large leaf rosettes
- Mountain houseleek (Sempervivum montanum): forms up to ten centimeters long runners, showy red flowers
- Dolomite houseleek (Sempervivum dolomiticum): extremely undemanding, pretty red flowers
- Large-flowered houseleek (Sempervivum grandiflorum): particularly large, yellow or white flowers, hairy leaves
- Cobweb houseleek (Sempervivum arachnoideum): interesting cobweb-like hairs in summer
Mexican Hens and Chicks (Echeveria)
Mexico as the origin of the rosette succulent Echeveria already indicates that in this genus the winter hardness is unfortunately limited. Only a few species such as Echeveria elegans or Echeveria agavoides are mentioned as hardy. Of course – if you don’t want to do without the Echeveria rosettes – you can also hibernate the Echeveria in the cold house.
Prickly Pear (Opuntia)
Opuntia, also known as prickly pear cacti, come from North and South America, with more than half of the approximately 190 different species native to Mexico. Many hardy opuntia grow shrubby or form a trunk, some form mats that cover the ground. Cold winters survive primarily those species from temperate climates. These include, for example, Opuntia fragilis, native to southern Canada, and its hybrids, as well as the extremely frost-hardy Opuntia howeyi from Mexico. These species, as well as Opuntia polyacantha and Opuntia macrocentra, are hardy to around minus 25°C, but absolutely need rain protection.