Sempervivum calcareum 'Guillaumes'

RHS Plant Profile

houseleek 'Guillaumes'

Synonyms

Sempervivum calcareum from Guillaumes, Mont Ventoux, France

Alpine Rockery Cactus Succulent

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An evergreen perennial producing rosettes, averaging 2cm in diameter, made up of spirally arranged, fleshy, green leaves suffused dark red starting at the tip and spreading down the leaf as it ages. The flowers are pale green and sticky, produced in clusters on long, stout 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: North–facing or East–facing or South–facing or West–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

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