Sempervivum arachnoideum Rubin

With its regular shape and silky rosettes of bright purple, Sempervivum arachnoideum 'Rubin' is one of the prettiest varieties of houseleek. One beautiful summer day, like a lovely surprise, a small star-shaped flower spike of bright carmine pink emerges from the heart of the oldest rosettes. This houseleek is a small succulent plant ideal for arid and mineral areas. It requires nothing more than an open location. Without any maintenance, it miraculously survives almost without soil, in a dry, poor, siliceous environment, and relies on rainwater, even if it is scarce.

From the Crassulaceae family, the cobweb houseleek is proof that poor soil and a mineral landscape can accommodate beautiful specimens with vibrant colours. This sempervivum is quite variable in appearance. It lives on rocks or in scree, dispersing its fine seeds in crevices and clinging to the smallest fissures to slowly form small colonies of rosettes of different sizes. It has been hybridised with other species, producing beautiful varieties characterised by the presence of silky filaments on the foliage.

The hybrid cultivar 'Rubin' was selected in Germany in 1937. It was later awarded by the Royal Horticultural Society. Its juxtaposed rosettes are tightly packed, and do not exceed 10cm (4in) in all directions at maturity. Over time, it can form a creeping cushion through its stoloniferous stems, spreading up to 50 to 60cm (20 to 24in) on the ground, perfectly following the terrain. Resembling a slightly open artichoke, each perfectly organised rosette is composed of numerous fleshy, pointed leaves without petioles. The white threads, stretched between the central leaves, shine in the sun, as do the cilia that line them. The light purple colour of the leaves intensifies in summer. Flowering appears on rosettes aged 2 or 3 years, which will then disappear, having ensured the plant's perpetuity by producing several small rosettes on the periphery. The flower spikes develop in summer, formed by thick stems that bear 1 to 5 flowers with 8 to 10 petals of bright carmine pink. The roots of this perennial are thick and long. They penetrate deeply into rock crevices, ensuring a good attachment to the walls while drawing water from the depths.

Sempervivum 'Rubin' is a boon for gardens where the soil lacks thickness. It thrives where few species survive, colonising abandoned spaces. You can still 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 low wall, or even a green roof. Houseleeks are easy-to-care-for succulent plants, offering flowers and foliage in various shades that create stunning compositions. Magnificent in pots, especially in low terrine-type pottery, they are irreplaceable in borders, troughs, or rockeries, alongside sedum, London pride (Saxifraga umbrosa), wall bellflowers, or Lewisia cotyledon. These miniature perennials quickly inspire the desire to multiply them. Consider choosing companions with staggered flowering times (thymes, Hertia cheirifolia, Saponaria ocymioides) and colourful foliage (Sedum spathulifolium) for a varied and joyful rock garden.