Sempervivum Rauher Kulm

Sempervivum 'Rauher Kulm' is a rarely offered hybrid houseleek that stands out with its beautifully coloured rosettes of purplish violet in winter. The tips of the leaves turn bluish-green from spring onwards. The succulent leaves lighten from the edges, and their undersides turn pale yellow-green in summer. Mature plants are adorned with beautiful pink flower stems with a darker centre. Easy to grow, this lovely perennial enhances rock gardens, walls, green roofs, and all rocky areas inhospitable to other plants. Once established, houseleeks like to be forgotten. These plants that seem to live off the air can also be grown in large pots.

Sempervivum 'Rauher Kulm' is a German creation by Dr Fritz Kühlein dating back to 1962. This hybrid variety is named after an old volcano near Bayreuth. Houseleeks naturally grow in lawns, on rocks and scree slopes, in open and sunny locations, mainly in mountainous areas. They belong to the Crassulaceae family.

The houseleek 'Rauher Kulm' is a succulent perennial with thick and long roots that penetrate deeply into rock crevices, providing good anchorage on the walls while drawing water from deep below. The plant slowly forms small colonies of differently sized rosettes, juxtaposed, reaching 5 to 7cm (2 to 3in) in diameter at maturity, and not exceeding 10cm (4in) in height. Over time, this houseleek can form a slightly loose or dense carpet through its stoloniferous stems, spreading up to 30cm (12in) on the ground, perfectly following the terrain. Resembling a spread-out artichoke, each rosette is composed of numerous ovate, concave, and pointed leaves with cilia, without petioles, overlapping each other. Their colour varies depending on their age, season, and climatic conditions. A soft purple, close to red wine, dominates in winter. Flowering appears on rosettes aged 2 or 3 years, which will then disappear, having ensured their perpetuity by producing a few small daughter rosettes on the periphery. The fluffy flower stems, 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 pink petals crossed by a dark pink median line. The centre of the flowers is a deep pink.

Sempervivum 'Rauher Kulm', like all houseleeks, is an excellent plant for dry or alpine rockeries. It thrives where few species survive. You can still enjoy this hardy perennial if your soil is poor, rather dry, rocky, stony, or even slightly calcareous. It withstands temperatures below -15°C (5°F)) and requires no maintenance. It promises to enliven any mineral decor. Houseleeks are unusual and easy-to-care-for succulent plants that you quickly become attached to. Their flowers and foliage with varied shades inspire the desire to collect them, multiply them, and create astonishing compositions in the most inhospitable places. They look stunning in low pots, especially in terrine-style containers. They are irreplaceable in borders, troughs, or rockeries, alongside wall bellflowers, paronychia, sedum, or Lewisia cotyledon. Consider choosing companion plants with staggered flowering (Antennaria dioica, thyme, delosperma, ficoides, Euphorbia myrsinites) to create a colourful and joyful rockery.