Sempervivum 'Sirius'

RHS Plant Profile

houseleek 'Sirius'

Synonyms

Sempervivum 'Sirius' (Star Series)

Cactus Succulent

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A mat-forming, evergreen succulent producing fleshy rosettes, in clusters, the spoon-shaped, bright green leaves, with dark, almost black tips. Tall stems of starry pink flowers produced from mature rosettes, die off after flowering in summer and are replaced by new offsets

Position

Full sun

Soil Types

Chalk, Loam, Sand

Max Height

Up to 10 cm

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 2–5 years
Max Spread: 0.1-0.5 metres
Max Height: Up to 10 cm

Growing Conditions

Chalk Loam Sand

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

Position

Full sun

Aspect: 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): H7

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 sharply-drained soil with added grit, in full sun. Protect from excessive winter wet. Suitable for rock garden, scree bed, wall crevice, trough or alpine house. See sempervivum cultivation for further advice

Propagation

Propagate by seed sown in spring, or root offsets in spring

Suggested planting locations and garden types

City and courtyard gardens
Coastal
Cottage and informal garden
Gravel garden
Patio and container plants
Rock garden
Low Maintenance
Flower borders and beds
Garden edging
Ground cover

Pruning

No pruning required

Pests

May be susceptible to sempervivum leaf miner and vine weevil

Diseases

May be susceptible to a rust