Question: succulent plants
Which small fat plants (not trees) are resistant to cold (even -5) and therefore can be placed in an external rock garden
Answer: succulent plants
there are many succulents that can live quietly in the garden, some unfortunately need special care, such as a dry soil for all the winter months, so they are not recommended in rock gardens, because they take the possibility of receiving water from the weather , you would practically condemn to death the other plants of the rock garden, which instead love these sporadic waterings.
Generally the succulent plants that are well resistant to frost - even up to -10 °, and even for prolonged periods of time - belong to particular genera, and they are small, creeping plants, which are well suited to the rock garden; these are often plants belonging to particular families of succulents, some of which are also present in the spontaneous flora of our country.
Certainly very resistant to the cold are the sedum: deciduous plants, which produce their thin stems in spring, with small fleshy leaves, often pale in color, sometimes tending to gray or blue; during the winter the sedum completely lose the aerial part, therefore they do not give any problem in cultivation. There are all sizes, from a few centimeters, up to 45-55 cm in height, with foliage of various shapes, and abundant flowering in summer or autumn.
The sempervivum are also very resistant to the cold: they form dense fleshy, evergreen rosettes; they are so resistant to the winter cold that some sempervivum live in the ravines between the rocks in the Italian Alps, where winter is always characterized by snowfall.
There are also several types of sempervivum, with rosettes of various sizes and more varied colors, with summer or spring flowering in shades of pink or yellow; the most famous sempervivum is sempervivum tectorum, so called because it has such spartan needs as to be able to develop even on the roofs, rooting in the substratum made up of decomposing material that is deposited between the tiles: it has green-gray fleshy foliage and yellow flowers , it is ground cover and develops quite quickly if it finds land available.
In the nursery in spring you can find various species of creeping succulents, with brightly colored flowers, in the shape of small daisies, which belong to various genera and species; they have often complicated names, and sometimes they are sold with particular fancy ones, they are called aptenia, carpobrotus, mesibrianthemo; dorotheantus, lampranthus, and so on.
These succulents are evergreen in nature, but only in areas where the winter climate is mild; if they are frozen, the aerial part dries up completely, and often recovers in spring, at the first heat. These plants are suitable for the rock garden, even if a mulch at the end of autumn can be useful if a very harsh winter is feared at the gates.
The lewisia also has the same behavior, but leaves arranged in thick flat and wide rosettes.