Sempervivum ciliosum var. borisii

Sempervivum ciliosum var borisii is one of the most decorative species of houseleeks, due to the mantle of long silky and silver bristles that cover its leaves. Its rosettes are small but globular and very dense. Together they form an unusual mosaic, whose luminous geometry perfectly matches the terrain of a rockery or a low wall. One beautiful summer day, like an unexpected gift, a small stalk of pale yellowish-green star-shaped flowers 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 and thin soil that does not retain water. Without any maintenance, it miraculously survives in deprived environments, relying solely on rainwater, even if it is scarce.

From the Crassulaceae family, this ciliate houseleek is proof that poor soil and a mineral landscape can accommodate beautiful plants with vibrant colours. Spontaneous in the Balkan massifs of Bulgaria, Greece, and Yugoslavia, this Sempervivum lives on rocks or in scree, dispersing its fine seeds in crevices and clinging to the smallest cracks to slowly form small colonies of rosettes of different sizes, juxtaposed, each not exceeding 10cm (4in) in height. Over time, it can spread through its stoloniferous stems to form a carpet spreading over 60cm (24in) on the ground, perfectly matching the terrain. Resembling tightly packed small artichokes in balls measuring 1.5 to 5cm (1 to 2in) in diameter, each rosette is composed of numerous wide and pointed leaves, without petioles, with a tender green colour with pink-red tips under their long silky bristles. The bristles that cover the leaves gleam in the sun and give the rosettes a superb silver shine. The roots of this perennial are thick and long. They penetrate deeply into rock crevices, ensuring good anchorage on the walls while drawing water from deep below. The flowering appears on rosettes aged 2 or 3 years, which will then disappear, having ensured their perpetuity by producing several small daughter rosettes on the periphery. The flowering stems develop in summer, formed by thick stems that bear 1 to 5 flowers with 8 to 10 pale-yellow petals and a green median.

Sempervivum ciliosum var. borisii is a boon for gardens where the soil lacks thickness. It thrives where few species survive and colonises abandoned spaces. If your soil is poor, rather dry, rocky, stony, or even slightly calcareous, you can still enjoy this hardy perennial (which withstands temperatures below -15°C (5°F)). It 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-grow succulent plants, offering flowers and foliage in various colours that create stunning compositions. Magnificent in containers, especially in low terrine-type pots, they are irreplaceable in borders, troughs, or rockeries, alongside London-pride (Saxifraga umbrosa), wall bellflowers, or Lewisia cotyledon. These very endearing perennials quickly inspire the desire to collect them. Remember to choose companions with staggered flowering times and colourful foliage for a varied and joyful rockery.