Sempervivum arachnoideum tomentosum description
Miniature, silver grey, cobwebbed rosettes.
It’s evergreen and has the occasional pink flowers in summer.
Can tolerate a coastal aspect with a certain amount of salt laden air.
How easy is it to grow:
This has won the RHS Award of Garden Merit . To win this impressive accolade the plants must have outstanding excellence for decorating a garden, be robust, not require highly specialist growing conditions or care and not be particularly susceptible to any pest or disease.
Good for in containers, alpine bed, rock garden, or by a patio and needs a bit of preparation because it resents the winter wet, so the soil must be very well drained and put gravel around the plant and under the rosettes.
Also, there must be no Vine Weevil in your garden (see ‘Care and maintenance’ below).
Sempervivum means ‘always alive’ which means they can survive with very little water – even being able to grow on a house roof (hence their common name).
Common name: Tomentosum Houseleek.
The best position in the garden:
What type of soil:
Gritty, well drained soil.
How much moisture:
Normal or dryish, stony.
Hardiness and, or, lifespan:
Hardy, but the drainage needs to be good.
Care and maintenance:
Rosettes that flower die and the baby rosettes carry on, so in late summer they may need the dead foliage cutting out.
It is susceptible to Vine Weevil which lay their eggs by the plant and these develop into white, banana shaped grubs that chomp the roots. Biological control is pretty good at controlling it.
Size of plant:
Height 15 cm.
Spread 15 cm.
Planting density – to calculate how many plants are required in a planting scheme:
Allow 40 plants per square metre.
Buy alpines online from Boundary Nursery.
 Royal Horticultural Society – opens in a separate window.