Sempervivum arachnoideum 'Cobweb'

Sempervivum arachnoideum 'Cobweb': Silvery Webs Spun Without a Spider

'Cobweb' looks like a spider moved in, then decided to decorate instead of hunt. Tiny green rosettes wrapped in white webbing. HALLOWEEN ALL YEAR, NO PLASTIC SPIDERS.

Plant Characteristics:

• Botanical Name: Sempervivum arachnoideum 'Cobweb'
• Common Name: Cobweb Hens and Chicks, Cobweb Houseleek
• Height: 5–10 cm (2–4 in), taller when in flower
• Spread: 15–30 cm (6–12 in), forming a mat of offsets
• Flowers: Starry pink flowers in flat clusters on short stalks
• Bloom Time: Summer (June to August)
• Foliage: Small, evergreen green rosettes, sometimes red-tinged, with white web-like hairs linking the leaf tips

Where to Plant: Because the rosettes are so small, give it a spot where people can lean in: troughs, rock garden pockets, the top of a stone wall, a crevice between paving stones or a shallow bowl on the patio. Massed, it makes a fuzzy silver mat.

Companion Plants: Tuck 'Cobweb' into a sunny gravel bed, trough or wall with lavender-blue pincushions, white gaura and orange butterfly weed. Scabiosa 'Butterfly Blue' adds lavender-blue pincushions at 30 to 45 cm from May to October. Gaura 'Monarch White' brings airy white flowers at 45 to 60 cm from June to September. Asclepias tuberosa adds bright orange butterfly weed at 30 to 75 cm in July and August. Schizachyrium 'Little Red Fox' grows to 60 to 75 cm and turns red and copper in fall.

Plant Care: Plant in full sun in gritty, very well-drained soil. Sand or fine gravel mixed in helps a lot. Avoid heavy clay and places where water pools, especially in winter and spring. In containers, use a cactus mix and a pot with drainage holes. Water to get it established, then only in long droughts. Skip the fertilizer. Lean conditions keep the rosettes tight and the webbing thick. Rosettes that bloom die afterwards. Remove them along with the dried stalk, and the surrounding chicks will fill in. Lift and replant chicks any time during the growing season.

History: Sempervivum arachnoideum grows wild in the mountains of Europe, from the Pyrenees through the Alps to the Carpathians. The species name means spider-like, after the web of hairs that protects its leaves, and the species holds the Royal Horticultural Society's Award of Garden Merit.

Final Thoughts: Tuck it in a trough or rock wall and let the chicks multiply. Deer skip it. THE ONLY COBWEB YOU'RE ALLOWED TO KEEP.