Mountain houseleek

Mountain houseleek: how do you recognise it?

Habit

Low, dense cushions 5–10 cm tall and 20–25 cm wide, built up of small rosettes.

Foliage

Rosettes 2–5 cm across with firm, fleshy, dark green leaves that are finely hairy and slightly sticky; sometimes tinged reddish brown.

Flower

Purple-red to pink stars with narrow petals, in July and August, on hairy stems 10–15 cm tall.

Runners

Short, thin stolons carrying small daughter rosettes; this is how the plant spreads.

Roots

Shallow and fine: the plant needs little soil and roots even in small crevices.

Flowering: July–August · Plants: March–September

Why grow it?

• Compact, evergreen rosettes that decorate all year, even in winter.
• Purple-red starry flowers in July and August, attractive to bees and other insects.
• Grows where almost nothing else will: poor soil, crevices, roofs, troughs and gravel beds.
• No watering, feeding or pruning; fully hardy.
• Makes new rosettes by itself, so you easily get more to plant and share.

Mountain houseleek: where does it grow best?

• Full sun is ideal; in light half shade the rosettes grow looser.
• Poor, very free-draining soil: sand or loam with plenty of grit or gravel. Preferably acid to neutral, so lime-poor.
• Dry: soil that stays wet causes rot, especially in winter.
• Plant 15–20 cm apart; the rosettes meet after a season or two.
• Ideal in rock gardens, troughs, gravel beds, on a wall top or on a roof.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Dry

Size

0.1 m tall, 0.25 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Stonecrop: Low sedums with the same poor, sunny needs, for example white stonecrop.
• Saxifrage: Small rosettes and flowers for a rock garden or trough.
• Creeping thyme: Scented mats between the rosettes.
• Blue fescue: Fine blue-grey tufts that contrast with the cushions.

Mountain houseleek: when and how to plant it?

Plant in March–September.

1. Plant from March to September; in spring and autumn the plant has the most time to root.
2. Make the soil poor and free-draining with coarse sand or grit. Use no compost or fertiliser.
3. Set the rosettes 15–20 cm apart with the base of each rosette just above the soil; do not bury the leaves.
4. Firm the soil well and water once, then only in prolonged drought.
5. Spread a thin layer of grit or gravel around the rosettes; it keeps the leaves dry and weeds down.

Care

Water

Not needed once established; in pots and troughs water only in prolonged drought.

Feeding

Avoid: rich soil gives soft, stretched rosettes.

Flowered rosettes

A rosette that flowers dies afterwards. Remove the dead rosette and flower stem and let the daughter rosettes fill the gap.

Dead leaves

Pick off withered leaves at the base so that moisture does not stay trapped.

Weeding

Remove weeds by hand from the cushions, because it is hard to weed without pulling out rosettes.

Tip: Use lime-poor soil with plenty of grit and never feed. Take a few daughter rosettes each year and plant them elsewhere: the cushion stays dense and you get new plants for free.

Mountain houseleek: when to prune it?

When: Pruning is not needed. Remove spent flower stems and dead rosettes after flowering, in August or September.

How:

• Cut the spent flower stem off at the base.
• Gently pull the withered mother rosette out of the cushion.
• Fill the gaps by setting daughter rosettes in them.

Pruning calendar and basic rules

Propagation

Daughter rosettes

From April to September: take a small rosette from a runner, preferably with a few roots, and plant it in poor soil. Without roots, press it onto sand; it roots within a few weeks.

Seed

In spring, sprinkle the dust-fine seed on sandy soil without covering it. Seedlings grow slowly and are ready to plant only after a year or two.

Mountain houseleek: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy to about −30 °C: no protection needed in Belgium.
• In winter the rosettes close up and sometimes turn reddish brown; this is normal.
• In pots and troughs, wet is more dangerous than frost: ensure good drainage and, if need be, stand them under an eave.

Diseases and pests

• Rot: Black, soft rosettes after wet spells. Plant them in soil with plenty of grit or move them to a drier spot.
• Vine weevil: The grubs eat the roots, so rosettes come loose. Look for white grubs in the soil and use beneficial nematodes from May to September.
• Stretched rosettes: Too much shade or feeding: the rosettes become loose and leggy. Give more sun, do not feed and replant stretched rosettes.
• Dying rosettes: A rosette that has flowered dies: this is normal. Remove it and let the daughter rosettes carry on.

Through the year

• March: Plant. Prepare poor soil.
• April: Plant. Detach and replant daughter rosettes.
• May: Plant. Remove weeds.
• June: Plant. On wet soil, watch for rot.
• July: Flowering with purple-red stars.
• August: Flowering. Remove spent stems and dead rosettes.
• September: Last chance to plant. Fill gaps with daughter rosettes.
• December: Rest. The rosettes stay green or turn reddish.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• Sempervivum comes from Latin and means always living.
• Each rosette flowers only once and then dies, but the daughter rosettes keep the plant going.
• In the Alps, mountain houseleek grows on rocks up to above the tree line.