Cobweb houseleek
Sempervivum arachnoideum ·
Small rosettes laced across the top with fine white hairs like a spider's web, forming tight, silvery mounds. Rose-pink flowers on short stalks appear in summer.
- Size
- 3 in tall, 10 in wide
- Zones
- 5 to 8
- Light
- Full sun
- Flowers
- Grown for its leaves; flowers late June to late July
- Pets
- Not checked
- Job in a bed
- Carpet
A bed built around cobweb houseleek
The planner designed this bed around cobweb houseleek when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 715 that suit those conditions and its dry soil, and says below why cobweb houseleek stands where it does.
The plants
- 1 Cobweb houseleek × 21, silver leaves
- 2 Cheddar pinks 'Tiny Rubies' × 21, pink
- 3 Brown-eyed Susan × 5, yellow
- 4 Little bluestem 'Standing Ovation' × 3, tan
- 5 Leadplant × 1, purple
- 6 Yellow coneflower × 5, yellow
- 7 Star of Persia × 2, purple
- 8 Spring starflower × 7, blue
Why this plant
- The only plant grown for its leaves. Leaf lasts all season, where a flower lasts a few weeks.
- A classic partner for Cheddar pinks 'Tiny Rubies'. Both are on this plan. A pairing gardeners have proved outranks a general rule.
Why here
- On the front edge. At 3 in it frames the bed without hiding it, and it is in leaf all season. It finishes 60% of the edge.
- 21 plants in 5 runs (5, 5, 5, 3 and 3). Runs of different lengths make the edge a frame, not a ruled line.
- Beside Cheddar pinks 'Tiny Rubies'. A recognised partner: the planner puts such plants together where it can.
Why now
- Here for its leaves, all year. They cover the 14 weeks between early March and late November when nothing on the plan is in flower.
- One of two evergreens. They are what the bed has to show from November to March.
Planned as an English border: 5 of the 6 groups (83%) are drifts, longer along the bed than they are deep. The bed is balanced: the left half carries 58% of the visual weight and the right half 42%. Cobweb houseleek and Cheddar pinks 'Tiny Rubies' finish the front edge.
The planner's own design check: 12 Excellent, 5 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where cobweb houseleek goes in a border
At 3 in it belongs at the front of a bed. In the planner's ten height classes it is ground-hugging (up to 6 in).
Its job: carpet. A groundcover planted in threes and fives to cover the soil: along the front, and just behind it.
The webbing makes the rosettes look silver. It needs the sharpest drainage of all; in a wall or on a slope, water runs off the crowns.
- Troughs and rock crevices
- Close-up detail
- Containers
What to plant with cobweb houseleek
Plants recorded as good partners for it, and what each pairing does:
- Hens and chicks: happy in the same dry soil.
- Sedum 'Angelina': happy in the same dry soil.
- Cheddar pinks 'Firewitch': adds the flowers, mid May to late June; tall enough (8 in) to stand behind it; happy in the same dry soil.
Questions about cobweb houseleek
Does cobweb houseleek need sun or shade?
Cobweb houseleek grows in full sun (6 or more hours of direct sun a day).
It wants dry, sharply drained soil, on the lean side, with no feeding, and little watering once settled.
What zones does cobweb houseleek grow in?
USDA zones 5 to 8. It is hardy to zone 5, which means it survives winter nights down to about −10 °F (−23 °C).
Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
How far apart should cobweb houseleek be planted?
6 in (15 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 10 in (25 cm), so a group knits into one patch.
It grows 3 in (8 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many cobweb houseleek plants do I need?
At 6 in apart, set out in staggered rows:
- 48 to fill 10 square feet (about 1 m²)
- 21 for a single row 10 ft (3 m) long
- 153 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as threes and fives, along the front and just behind it.
In the bed above, the planner used 21 in five groups.
Is there a native plant like cobweb houseleek?
Cobweb houseleek is not native to North America. These North American natives come closest to doing its job:
- Bird's-foot violet: the same size; a drift, not a carpet, flowers late April to late May.
- Pussytoes: the same job in a bed; 6 in wider, fine leaves, not medium.
- Beach wormwood 'Silver Brocade': the same job in a bed; 5 in taller, 12 in wider.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What does cobweb houseleek look like in winter?
Cobweb houseleek keeps its silver leaves all winter, so it is one of the plants that hold a bed together from November to March, when the perennials have gone.
More Sempervivum
- Hens and chicks Sempervivum tectorum
In these guides
Every fact on record
- Type
- Perennial
- Size
- 3 in (8 cm) tall, 10 in (25 cm) wide
- Plant
- 6 in (15 cm) apart
- Height class
- Ground-hugging (up to 6 in)
- Place in the bed
- Front
- Flowers
- Late June to late July; dense clusters; pink
- Leaves
- Medium texture, evergreen; silver
- Shape
- Mounding, spreading
- Hardy in
- USDA zones 5 to 8
- Light
- Full sun
- Soil
- Lean, dry and sharply drained
- Water
- Low
- Feeding
- None needed
Not yet checked against an outside reference: its figures rest on general horticultural knowledge. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.