Sempervivum calcareum 'Sir William Lawrence'

RHS Plant Profile

houseleek 'Sir William Lawrence'

Alpine Rockery Cactus Succulent

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'Sir William Lawrence' is a mat-forming, evergreen, succulent perennial forming rosettes of fleshy, ovate, and pointed grey-green leaves tipped with maroon red, each rosette around 2cm in diameter. Clusters of sticky, pale green flowers flushed with purple are borne on short stems in summer

Position

Full sun

Soil Types

Loam, Sand

Max Height

Up to 10 cm

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 0.1-0.5 metres
Max Height: Up to 10 cm

Growing Conditions

Loam Sand

Moisture: Well–drained
pH: Acid or Alkaline or Neutral

Position

Full sun

Aspect: South–facing or North–facing or West–facing or East–facing
Exposure: Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H5

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Crassulaceae
Native to GB/Ireland: No
Foliage: Evergreen
Habit: Matforming
Genus: Sempervivum are evergreen perennials forming mats of fleshy-leaved rosettes, often attractively coloured, with star-shaped pink or pale yellow flowers in summer
Name Status: Accepted

How to Grow

Cultivation

Grow in moderately fertile well-drained soil in full sun. Protect from excessive winter wet. Suitable for rock garden, scree bed, wall crevice, trough or alpine house

Propagation

Propagate by rooting offsets in spring

Suggested planting locations and garden types

Patio and container plants
City and courtyard gardens
Coastal
Cottage and informal garden
Gravel garden
Rock garden
Garden edging

Pruning

Carefully remove spent rosettes after flowering

Pests

May be damaged by sempervivum leaf miner, slugs and snails, and vine weevil larvae

Diseases

May be susceptible to a rust