Sempervivum calcareum Sir William Lawrence description
Globular blue-green rosettes with brown tips turning to red tips.
It’s evergreen and has the occasional pink flowers in the 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.
This is similar to Sempervivum calcareum in late spring and Sempervivum calcareum Mrs Giuseppi in the summer.
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: Sir William Lawrence 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 20 cm.
Planting density – to calculate how many plants are required in a planting scheme:
Allow 25 plants per square metre.
 Royal Horticultural Society – opens in a separate window.