UK compost
What compost for cobweb houseleek in the UK?
Sempervivum arachnoideum
More about cobweb houseleek in the UK
Which compost cobweb houseleek needs
For cobweb houseleek the mix to buy is peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Sharp drainage is essential: succulent compost with plenty of grit, perlite or coarse sand, or a gravelly alpine mix. Never use heavy, water-retentive soil.In British garden centres the bagged growing medium is sold simply as “compost” (multipurpose, ericaceous, or loam-based John Innes), which is a different thing from the rotted garden “compost” you make in a heap — for a pot you want the bagged kind.
Peat-free compost
Buy peat-free. The sale of peat compost to home gardeners is being phased out across the UK, and the RHS recommends peat-free on environmental grounds. A good peat-free multipurpose grows cobweb houseleek perfectly well; the one habit to change is watering — peat-free dries faster at the surface while still moist below, so check by feel a knuckle deep rather than trusting the look of the top.
Ericaceous or multipurpose?
Cobweb Houseleek does not want a rich, water-holding compost — it wants sharp drainage. Cut peat-free multipurpose roughly half-and-half with horticultural grit, sharp sand or perlite, and always pot into a container with drainage holes. A "cactus and succulent" bagged mix is a ready-made shortcut.
For the full recipe, pH and drainage detail (US wording), see the cobweb houseleek soil & potting-mix guide.
Compost for Cobweb Houseleek in the UK — frequently asked questions
What compost should I use for cobweb houseleek in the UK?
Use peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Sharp drainage is essential: succulent compost with plenty of grit, perlite or coarse sand, or a gravelly alpine mix. Never use heavy, water-retentive soil. In UK garden centres this is sold simply as "compost" — the bagged growing medium, not garden-made leaf-mould — so match the description above rather than a brand.
Can I use ordinary multipurpose compost for cobweb houseleek?
Not on its own — multipurpose compost holds too much water for cobweb houseleek and will rot the roots. Cut it roughly 50:50 with horticultural grit, sharp sand or perlite so it drains fast.
Should the compost be peat-free?
Yes. Sales of peat compost to home gardeners are being phased out in the UK, and the RHS recommends peat-free for environmental reasons. Modern peat-free multipurpose composts grow cobweb houseleek perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does cobweb houseleek need grit or perlite added?
Yes — cobweb houseleek must have sharp drainage. Add about one part horticultural grit or perlite to one part compost, and always use a pot with drainage holes.
What pot and drainage does cobweb houseleek need?
Always a pot with drainage holes. Gritty, fast-draining alpine/succulent mix. Stand it on a saucer, empty any water that collects after watering, and never leave the pot sitting in a full outer cover — waterlogged compost in a cool UK room is the commonest cause of root rot.
More cobweb houseleek care
See the full cobweb houseleek care guide, its UK watering and UK hardiness.