Hens & Chicks - Red Cobweb

Sempervivum arachnoideum 'Rubrum'

Crassulaceae

• Full sun
• Rosettes ~0.5"–1.5"; mat 1"–4" tall x 5"–10" wide
• Drought Tolerance: High; requires lean, gritty, sharp-draining soil; protect from winter wet
• Foliage: Evergreen ruby-red rosettes veiled in fine white cobweb-like hairs; reddens further in sun/cold
• Flower & Habit: Starry pink flowers in summer; monocarpic, spreads by offsets
• Wildlife Benefits: Bees at bloom; deer and rabbit resistant

Cobweb houseleek is one of the most distinctive of the hens and chicks, a tiny alpine succulent native to the mountains of Europe. The 'Rubrum' highlights natural red coloring into deep ruby and wine tones. Like all Sempervivum it is exceptionally cold hardy and drought tolerant, and its needs are simple: full sun, and the sharpest possible drainage in lean, gritty, rocky soil. It stores water in its fleshy leaves and rarely needs irrigation once established.  Standing moisture, and above all wet soil sitting around the crown in winter, will rot it. 

The feature that names this plant is unmistakable: each small rosette is laced across its tips with fine white hairs that stretch from leaf to leaf like a delicate spider's web. On the red-leaved 'Rubrum' the effect is especially striking, the silvery webbing set against dark ruby foliage that deepens further in cool weather and strong sun. The rosettes are very small, often only half an inch to an inch and a half across, forming a dense low carpet just an inch or few high but spreading five to ten inches wide. In summer mature rosettes push up short stalks topped with starry pink flowers. It is worth noting for customers that the cobweb hairs are a natural ornamental trait, not a pest or disease.

The pink summer flowers attract bees and other pollinators, and the plant is deer and rabbit resistant. It is a non-native ornamental valued for its toughness, its water thrift, and its jewel-like detail. It shares the houseleeks' traditional folk uses, the cut leaves historically applied like aloe to soothe burns and minor skin irritation.

'Rubrum' is a delight for the smallest, most detailed plantings: troughs, alpine pans, wall crevices, rock gardens, green roofs, and living-mosaic or vertical arrangements where its fine webbing can be seen up close. Its shallow fibrous roots hold soil in vertical and sloped settings. It combines beautifully with other small succulents and alpines, low sedums, and other Sempervivum to build a collection of contrasting rosette forms. Site it where people will pass close enough to appreciate the cobweb effect.