Sempervivum marmoreum Pilatus

Sempervivum 'Pilatus' forms a superb carpet of coloured rosettes ranging from bronze to mauve-violet, with hints of pink in full light, and bordered by long silver cilia that shine like frost in the sun. In winter, they will be greener. Its pink flowering in small stars occurs on a beautiful summer day, emerging from rosettes aged 2 to 3 years old. It is an excellent variety of houseleek, with rapid growth, ideal for embellishing arid and mineral areas. This small succulent plant requires nothing more than an open location and dry soil without thickness. Without any maintenance, it miraculously survives in deprived environments, and relies on rainwater, even if it is scarce.

'Pilatus' is a Swiss cultivar dating back to 1967 resulting from the cross-breeding between the variety 'Alpha', possessing the genes of the cobweb houseleek, and the species Sempervivum marmoreum. All houseleeks grow spontaneously in rocky grassland, on rocks and scree, in open and sunny locations, mainly in mountainous areas. They are very hardy succulent perennial plants of the Crassulaceae family that retain their foliage even in winter. 

The 'Pilatus' houseleek has thick and long roots that penetrate deeply into rock crevices, ensuring a good grip on the walls while drawing water from the depths. The plant quickly forms beautiful colonies of rosettes of different sizes, juxtaposed, reaching 8cm (3in) in diameter at maturity, and not exceeding 7 to 8cm (3in) in height. Over time, this houseleek can form an extremely dense mat through its stoloniferous stems, spreading over 40 to 50cm (16 to 20in) on the ground, perfectly following the terrain. Each pruinose rosette is composed of numerous spatulate leaves with pointed tips, without petioles, imbricated one into another, bordered by short silver hairs. Their colour varies according to the season and climatic conditions. In summer, dark shades such as mauve, violet, purple, and bronze dominate. In winter, due to the cold and decreased sunlight, the leaves will be rather greenish-bronze, with shades of chocolate. The flowering appears on rosettes aged 2 or 3 years old, which will then disappear, having ensured the plant's perpetuity by producing several small rosettes on the periphery. The fluffy flower stalks, 15 to 20cm (6 to 8in) tall, develop from June to August, formed by thick stems that bear 1 to 8 star-shaped flowers with 8 to 12 petals in shades of pale-pink crossed by a purplish-pink median line. 

Sempervivum 'Pilatus' is a boon for gardens where the soil lacks depth. It thrives where few species survive and colonises abandoned spaces. You can enjoy this hardy perennial if your soil is poor, rather dry, stony, rocky, or even slightly chalky. It withstands temperatures below -15°C (5°F), requires no maintenance, and promises to bring life to any pile of stones, a wall, or even a green roof. Houseleeks are very easy-to-care-for succulent plants, offering flowers and foliage in various hues that will create stunning compositions. Magnificent in their pot arrangements, especially in low terrine-type pottery, they are irreplaceable in borders, troughs, or rockeries, alongside London pride (Saxifraga umbrosa), wall bellflowers, or Lewisia cotyledon. Consider choosing companions with staggered blooms (antennaria, small sedums, delosperma) and colourful foliage (Tanacetum densum subsp. amanii, Ajania pacifica, Hertia cheirifolia), for a varied and joyful rockery.