Sempervivum arachnoideum

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cobweb houseleek

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cobweb houseleek RHS
cobweb houseleek RHS
cobweb houseleek RHS 2002

Other common names

cobweb sedum

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Alpine Rockery Cactus Succulent
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An evergreen perennial, forming a mat of fleshy rosettes 1-3cm across, leaves green or reddish, with cobwebby white hairs at the tips. Starry pink flowers 1cm in width appear in flat cymes on stems to 12cm 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)
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
Correct
Plant Range
Pyrenees to Carpath.

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 seed sown in spring, or root offsets in spring

Suggested planting locations and garden types

  • Cottage and informal garden
  • Gravel garden
  • Patio and container plants
  • Rock garden
  • Flower borders and beds
  • Garden edging
  • Ground cover

Pruning

No pruning required

Pests

May be susceptible to vine weevil

Diseases

May be susceptible to a rust