High in the mountains of Europe, conditions are typical for succulent plants: lean, gravelly soils, wind, intense sunlight and long periods without rainfall. In this trying environment, where winter sees some of the best ski slopes in the Alps, a group of succulents evolved to take it all in stride. Their only difference from the popular succulents of South Africa and Mexico is a remarkable tolerance for cold.
This is the doorway through which all gardeners may enter to discover the miracle of succulent tissues as a means of survival in a hostile environment. Many of them may appear identical to those being grown in the succulent meccas of Los Angeles and San Diego, but these are much tougher. Some were well known a century ago as our grandmothers nurtured their hens-and-chicks. Those known as house leeks were grown in the thatched roofs of England's cottages, which shows just how little soil they need to thrive. Remember, high alpine soils tend to be decomposed granite with fast drainage and little nutrition.
These are known as hardy alpine succulents, and the most fascinating genera is Sempervivum, which is botanical-speak for "live forever." When breeders started in, they worked to increase natural color, making it ever brighter, so these plants are gorgeous every day. A good way to dial in on the hardier species of Sempervivum is to look for the place of origin. If it's from Mexico or other warm parts of the world, its one of the tender species. If it's designated as European, then you've got a hardy choice.
Sempervivum grow in tidy little rosettes of leaves. Species can range from a tight golf ball to a more open plant close to the diameter of a softball. The first rosette termed the "mother plant" puts out "pups" around herself to gradually increase the size of a clump. When she flowers, she will die afterward, but the pups are there to take over. Each pup is a potential new plant that's easy to propagate by severing and rooting in sand.
Sempervivum tectorum (Zone 4) is the true house leek of Europe, and the largest species. Most of the really showy varieties result from its natural tendency to flush burgundy on its leaves. Breeders developed all-red or -purple plants with truly outstanding color.
Equally well known is Sempervivum arachnoideum (Zone 5), and is easy to identify because its leaves are covered with cobwebby hairs. This species produces some of the most outstanding floral displays with its many varieties. The small tight rosettes can fill gaps between rocks in the garden or fill out a wide, shallow container with color and interest.
Sempervivum montanum (Zone 5) is the wild card for breeders because there is such natural variation within this species. Its diverse color genes and magnificent flowers make it a wild card for breeders.
The genus Jovibarba now houses some of the species formerly considered Sempervivum. This group has great potential for home gardens.
The traditional way to grow these hardy alpines is in a rock garden with a solid southern exposure and perfect drainage. To learn more about growing in a rock garden, explore "Hardy Succulents" by Guen Kelaidis.
Where a rock garden isn't feasible, the plants can be grown in concrete, hypertufa or stone troughs filled with sandy, gravelly soil.