<em>Sempervivum</em>, houseleek: to plant, to grow and to care for

Description and botany

Sempervivum, or houseleeks, are perennial succulent plants forming rosettes of fleshy leaves. They are very low-growing, with a cushion, matting habit, the rosettes remaining at ground level. They originate mainly from mountainous regions of southern and central Europe and western Asia. There are about 35 species, forming a fairly diverse group. Horticultural varieties have also been developed for their ornamental qualities… more than 3,000 exist, providing enormous diversity in shape and colour. Houseleeks have been cultivated for a very long time. They were once planted on roofs and reputed to protect against lightning. Sempervivum tectorum is indeed called “roof houseleek”.

In France, seven different species occur in the wild, including Sempervivum arachnoideum, S. montanum, S. calcareum, S. tectorum… they are mainly found in mountainous regions (Alps, Pyrenees, Massif Central…), up to 3,000 metres altitude, in open rocky habitats: rocks, scree, dry short grass meadows and stony ground, cliffs, low stone walls… Sempervivum tectorum also grows on old stone walls. As mountain plants, houseleeks are naturally very hardy and can be grown across metropolitan territory. In the garden, a rockery is ideal, as it is the cultivation mode closest to their native habitat.

Sempervivum montanum: botanical illustration

Houseleek is a succulent plant (“full of juice”), exactly like sedums. It stores water in its tissues to resist drought, which gives it a fleshy appearance linked to its thick leaves. It is truly adapted to arid conditions!

Houseleeks belong to the large family Crassulaceae, which brings together nearly 1,500 species. Sedums, echeverias and kalanchoes are also in this family. These are mainly succulent plants, with fleshy, swollen tissues (leaves, branches or trunk serve as storage organs to hold water and minerals)… Indeed, the name Crassulaceae comes from Latin crassus, meaning “thick, heavy”! These plants are particularly adapted to life in very dry environments.

Sempervivum are very close to genus Jovibarba, but their flowers differ in shape (campanulate, bell-shaped, in Jovibarba, and star-shaped in Sempervivum). Both genera are commonly called houseleeks. The form of these plants is also similar to Aeonium.

The common name houseleek comes from Latin Jovis barba, “beard of Jupiter”, because the plant was believed to protect houses from lightning, Jupiter’s attribute. Sempervivum comes from Latin semper: always, and vivum: living… because of these plants’ great resistance to extreme conditions, and because the rosettes remain present in winter, being evergreen. The houseleek stays alive whatever the season or conditions!

The species name S. tectorum means “roof houseleek”. Other names indicate morphology or habitat: S. montanum: “mountain houseleek”; S. arachnoideum: spiderweb-like; S. calcareum: limestone houseleek; S. grandiflorum: large-flowered, etc.

Houseleeks are very low-growing, their rosettes remaining at ground level. They can be described as “stemless”: without a stem (in reality with an extremely reduced stem to which the leaves attach). With their matting habit, houseleeks hug the relief and shape of the rocks or rockeries where they are planted. Generally, they measure less than 10 cm tall, but gain a little height when in flower.

Rosettes of houseleeks resemble small, flattened, spreading artichokes. Their diameter generally ranges from 2 to 10 cm. They are small in Sempervivum arachnoideum, not exceeding 3 cm, and much larger in Sempervivum ‘Commander Hay’. Rosettes are semelparous: they flower once and then die… however, each gives rise to offsets that take over and replace them.

Houseleeks produce offsets, new rosettes borne on stolons (aerial stems). These enlarge progressively and root at contact with the soil. They can be produced some distance from the parent rosette or very close, pressed against it. They allow the plant to spread to form attractive mats and to regenerate, since each rosette dies after flowering and is replaced by offsets. Houseleeks can therefore remain in place for a very long time in the garden, renewing themselves regularly. The lifespan of a single rosette is short, but that of a whole clump is very long. It is very easy to multiply houseleeks by dividing these rosettes.

Houseleeks have roots that penetrate deeply, drawing water and minerals from deep in the soil. They anchor the houseleek well, making it adapted even to unstable environments (scree, rockeries…) or where very little substrate exists. The plant “clings” to its support thanks to deep roots capable of slipping into cracks between stones.

Houseleeks bear small, fleshy, thick leaves arranged all around a small central stem. Their fleshy nature allows them to store water and minerals to resist drought, as with cacti and other succulents.

Leaves are inserted in a helicoid fashion, forming a spiral when the rosette is viewed from above. Houseleeks are exceptionally graphic plants, evoking a superb rosette. Generally, leaves are inserted rather densely (probably reducing water loss by evapotranspiration and better insulating the plant against extreme temperatures). This trait is strongly marked in Sempervivum ciliosum, which forms small globose rosettes, well rounded with very imbricated leaves. Similarly, rosettes of Sempervivum globiferum form small, very rounded spheres. They are original and amusing.

Houseleeks offer great diversity in foliage, in both shape and colour. Leaves can be quite narrow and long, or rather flat and broad. They usually measure between 0.5 and 5 cm in length, and may be spatulate, oblong, obovate… Often tapered to a pointed tip. Leaf shape is surprising in variety ‘Grigg Surprise’: elongated, rounded in section and curved “like a claw” at the tip.

They often take reddish, purplish or bronze hues… Hybridisation has produced thousands of varieties in the widest range of shades. Rosettes of variety ‘Alpha’ are purplish – deep red – contrasted by the white cilia that underline the lamina edge. Rosettes of ‘Chick Charms Gold Nugget’ are striking with a bright yellow-orange tone. ‘Cherry Berry’ shows a lovely red tint, while ‘Dark Beauty’ is very dark purple, almost black. Generally, leaves often end in a reddish point (very noticeable in Sempervivum calcareum!). Leaves can also be bluish, as in ‘Pacific Blue Ice’; or even yellow: ‘Cmiral’s Yellow’! This last variety is ideal for adding brightness and playing with colour, for example combined with sedums of varied shades.

Sometimes houseleeks show several tones: Sempervivum tectorum ‘Sunset’, for instance, offers a superb red and pale green (almost yellow) contrast. In some varieties only the tip and edge of the leaf are coloured red or black, which nicely emphasises the spiral form.

Houseleeks tend to change colour with seasons, temperature and sun, varying between green, red, bronze or purple depending on species.

Rosettes of houseleeks can take varied hues: Sempervivum ‘Othello’, Sempervivum ciliosum var. borisii (photo Stephen Boisvert), and Sempervivum calcareum

In Sempervivum arachnoideum, the rosette centre is covered with many fine white threads resembling a spider’s web… hence its name. Likewise, in Sempervivum ‘Boule de Neige’, rosettes form white balls covered with fine white threads. These houseleeks have a very soft appearance. Sometimes leaf margins are ciliate, producing a lovely frosted effect. Hairs glint in the sun. Leaves can be glaucous, as in Sempervivum ‘Othello’.

Rosettes of houseleeks are evergreen. They remain present all year round, summer and winter alike!

Houseleeks take several years, often between two and four, before flowering. Flowering generally occurs in early to mid-summer (between June and August), on rosettes that are already two to four years old. A flowering stem then develops, reaching up to 20 cm high. It really seems an extension of the rosette, which suddenly erects and grows in height. The floral stem is covered with leaves (or scales) resembling those of the rosette. It is somewhat branched at the top where the flowers are grouped in a paniculate cyme.

Houseleeks bear beautiful, star-shaped flowers, rather original. They are refined in appearance, with much detail due to numerous floral parts. Flowers often have between 8 and 15 petals, and usually an even higher number of stamens. Petals are fairly narrow and radiating, giving a star shape. They surround a circle of stamens. Flowers are hermaphrodite, bearing male and female organs. However, stamens open before the pistil, helping to avoid self-fertilization.

Flowers are generally pink, red or yellow… often of a muted shade rather than bright, such as pale pink tending to brown, pale yellow, pinkish white or greenish… Flowers are a lovely pink in Sempervivum arachnoideum, yellow in Sempervivum ciliosum… Petals often have a darker midline, adding detail and contrast.

In general, stamen colour harmonises nicely with petal colour. They are often darker, with a slightly stronger tint, drawing the eye to the flower centre. Stamens are red in Sempervivum montanum.

Flowering of houseleeks: Sempervivum tectorum ‘Metallicum Giganteum’ (photo H. Zell), pollination of a houseleek flower, and Sempervivum grandiflorum (photo Stan Shebs)

After flowering, houseleeks produce follicles, dry fruits that open when ripe to release the many tiny brown seeds they contain. Seeds can be collected and sown, but it is much simpler to propagate by division. As rosettes are semelparous, they die after producing seeds.

Despite their succulent appearance, houseleeks are very hardy and can be cultivated even in fairly cold regions, for example in mountains.

Main varieties of Sempervivum

Most popular varieties

Our favourite varieties

Other varieties to discover

Sempervivum arachnoideum

This houseleek produces rosettes with fairly rounded shapes, notable for being covered in very fine white threads, reminiscent of spider webs. It bears pretty pink flowers. Recipient of the RHS Award of Garden Merit by the Royal Horticultural Society (RHS).

• Flowering time July, August
• Height at maturity 8 cm

See the product sheet

Sempervivum Othello

A superb houseleek variety whose rosettes are green at the centre and rather red towards the outside, with outer leaves well spreading and elongated. Recipient of the RHS Award of Garden Merit by the Royal Horticultural Society (RHS).

• Flowering time July to September
• Height at maturity 10 cm

See the product sheet

Sempervivum tectorum

This is the roof houseleek, as found naturally in France. It forms elegant rosettes made up of fairly broad, tapered leaves. Leaves are green and end in a reddish point, which gracefully emphasises their shape. Recipient of the RHS Award of Garden Merit by the Royal Horticultural Society (RHS).

• Flowering time July, August
• Height at maturity 10 cm

See the product sheet

Sempervivum Chick Charms Gold Nugget

An impressive variety for its splendid colours, which change over time. Leaves are green in summer and turn yellow-orange in autumn, the rosette then evoking a bright, radiant sun.

• Flowering time July to September
• Height at maturity 10 cm

See the product sheet

Sempervivum Commander Hay

A superb variety that generally bears reddish leaves with green tips. Its hue evolves over time, offering a lovely range between green and red.

• Flowering time July, August
• Height at maturity 10 cm

See the product sheet

Sempervivum calcareum

This botanical species forms elegant rosettes with green leaves ending in red points, creating a magnificent contrast and emphasising the plant's rosette form.

• Flowering time July, August
• Height at maturity 10 cm

See the product sheet

Sempervivum ciliosum var. borisii

A charming variety that forms globular rosettes made up of numerous small imbricate scales densely arranged.

• Flowering time July, August
• Height at maturity 10 cm

See the product sheet

Sempervivum Chick Charms Cherry Berry

This houseleek takes on a beautiful deep dark red hue in summer and into autumn, while becoming rather green in autumn and winter. Its rosettes are particularly elegant, composed of numerous leaves imbricated into a superb rosette. It also produces star-shaped pink flowers.

• Flowering time July to September
• Height at maturity 8 cm

See the product sheet

Sempervivum Dark Beauty

A houseleek with very dark tones, purple almost black. Ideal for creating contrast effects alongside plants of lighter colours, enabling a graphic, modern and original rockery.

• Flowering time July to September
• Height at maturity 10 cm

See the product sheet

Sempervivum marmoreum Pilatus

This houseleek offers an original and quite dark hue, oscillating between purplish-red and dark green, with some bluish nuances. Its colour is therefore quite unique. Its leaves are edged with white cilia, highlighting the exceptional pattern of each rosette.

• Flowering time July to September
• Height at maturity 10 cm

See the product sheet

Planting houseleeks

Where to plant?

Place houseleeks in full sun, as they need plenty of light. However, although they are fairly tough and drought-adapted, houseleeks do not like very hot conditions. If you live in a Mediterranean area, it is preferable to position them in partial shade for some protection. In other regions, place them in full sun.

They prefer rocky or stony soils that drain well. Avoid substrates that retain water, as these plants dread excess moisture, especially in winter. To grow them, it is always best to improve drainage by adding gravel or coarse sand at planting. Also consider planting on a mound or slope so water can run off easily.

Houseleeks can grow on very poor ground and need very little substrate. Thus, they can be placed on an old stone wall, in crevices… or even on a green roof! They are ideal in a rockery, as this closely resembles their natural habitat. It is also possible to create a composition in a pot or trough, for example with sedums and other small plants. Houseleeks allow you to bring greenery to places where other plants would struggle. You can easily grow them even without a garden… a simple windowsill is enough! As they do not need much soil or maintenance, houseleeks can be installed on any type of support or object: in bowls, troughs, pottery, or suspended in an improvised container…

As houseleeks are mountain plants, they are very hardy and can be grown even in quite cold regions, without requiring winter protection. The only precaution concerns excess moisture. If you live in a rainy area, they may need shelter in winter, protected from rain and standing damp… and above all they will require a well-draining substrate.

When planted in a confined space (pot, crevice, in a rockery between stones), Sempervivum will grow and produce offsets until the whole area is occupied. They fill available space well.

As houseleeks are small plants, to display them it is preferable to place them on a raised bed or in a pot, but at a height above ground level. They will be easier to admire if you plant them in a pot or arrangement that you place, for example, on a table on your terrace, or if you plant them in the crevices of a wall, rather than planting them at ground level in a conventional bed.

Houseleeks can adapt to the most varied situations. They are able to grow almost anywhere: in a pot (photo Magnus Manske), on a roof (photo Arnoldius), in old shoes or boots… but also on low walls, in rockeries, in troughs, or suspended…!

When to plant?

You can plant Sempervivum in spring or autumn, when temperatures are mild. Avoid periods of frost.

How to plant?

For planting in the ground:

1. Start by preparing the site. You can create a rockery by adding stones, gravel… Ideally, we suggest planting on a mound or slope so water can run off rather than collect. In any case, it is preferable to mix gravel or coarse sand into the planting soil to improve drainage.
2. Dig a planting hole, not necessarily very deep.
3. Take houseleek out of its pot and plant it.
4. Replace soil around it.
5. You can optionally add a layer of small gravel to the surface around the rosette, as this prevents water from pooling at the collar while limiting weed growth.
6. Water lightly.

It is generally not necessary to continue watering; rain should be enough to meet the plant’s modest needs.

→ Also read: How to plant succulents in the garden?

For container planting:

1. Choose a container, preferably with a hole in the bottom, and add a layer of gravel to aid drainage.
2. Then add a well-draining substrate, for example a mix of potting compost and coarse sand (a cactus compost can also be suitable).
3. Plant your houseleek.
4. You can add a layer of small stones to the pot surface to prevent water stagnating at the collar.
5. Place the pot in full sun (possibly in partial shade if you live in southern France).

For winter, you can move it to a place sheltered from the rain.

If you plant on a wall, on a roof, between stones, or in another type of container, we recommend creating a small pocket of potting compost so the houseleek has a minimum of substrate in which to establish.

Watch our video tips – How to successfully plant alpine perennials in a rockery:

Care

Once established, Sempervivum plants need almost no maintenance. They are hardy plants, tolerant of both cold and drought. In general, rainwater is sufficient to cover their water needs. You can nevertheless give occasional waterings during dry spells, but avoid excess moisture. Similarly, Sempervivum grow well in poor soil and do not require fertiliser applications.

You can tidy up clumps occasionally, remove faded inflorescences, cut away damaged parts, divide rosettes, and remove material that might cover them: dead leaves in autumn, plant debris, other plants growing alongside… Sempervivum should be kept in full sun. Feel free to prune surrounding plants to prevent them shading the rosettes. Similarly, as rosettes die after flowering, you can remove those that have dried out. We also recommend dividing them from time to time to rejuvenate them and give them more room to develop.

Concerned with diseases, Sempervivum can be affected by rust (Endophyllum sempervivi), which appears in cases of standing moisture. It is a fungus that parasitises the Sempervivum, causing deformation of the leaves: they become excessively elongated, take on a much paler hue, and bear orange pustules. Their appearance therefore changes completely. The pustules contain spores, allowing the fungus to multiply. If you notice this disease, we suggest removing affected rosettes to prevent its spread. You can also treat with a fungicide. Also limit waterings and improve drainage if necessary.

In any case, the main cultivation problem you may encounter with Sempervivum is linked to excess moisture. It is therefore important to plant them in a well-draining substrate. Likewise, placing gravel around rosettes helps prevent water pooling and causing rot. And if you live in a rainy area, it is preferable to protect Sempervivum: if grown in a pot, you can easily place it under cover; otherwise, consider installing a small rain shelter. Pubescent, silky varieties are more susceptible than others to winter moisture.

Multiplication

Division is the most commonly used technique, as it is easy and quick and reproduces the variety identically, but it is also possible to sow houseleek seeds.

Division

They are very simple to divide! Each houseleek rosette produces new rosettes, just beside the first, or attached to a stolon. So just separate them. Best to do this in spring, around April. Ideally wait until the offset has produced some roots and the stolon begins to wither and die back. But they multiply easily even without this.

1. Locate a rosette that has produced offsets.
2. Separate them by cutting the stolon, close to the original young plant, using a sharp knife.
3. Trim the stolon so that about 4 cm remain under each small rosette taken. Let these rosettes dry for several days (this allows the wound to heal).
4. Replant them, in pots or in open ground, in a well-draining mix (potting compost and sand).
5. Water lightly.

Over time, rosettes will grow larger and in turn form new offsets.

Uses and companion planting in the garden

Obviously, you can easily plant Sempervivum in a rockery or on a low wall (even on a green roof), with other small plants that will grow in little substrate, are drought-resistant and enjoy full sun. Plant them, for example, with sedums, saxifrages, rockroses, euphorbias (notably Euphorbia myrsinites)… as well as Delosperma, which offers very pretty pink-mauve flowers and fleshy foliage. You can also enjoy small Phlox subulata, which in spring are covered with a multitude of bright, often vivid flowers. In general, favour plants with a cushion or carpeting habit.

You can place Sempervivum at the front of a rockery, and put slightly taller plants behind them, which will bring volume: achilleas, lavender, agave, rockrose, phormium, phlomis… Avoid placing them too close so they are not smothered or shaded. Feel free to also include some ornamental grasses (Carex comans, blue fescue, Lagurus ovatus…), for the graphic effect and lightness they bring! You can even plant small rockery ferns such as Cheilanthes lanosa or Asplenium ceterach.

You can perfectly install Sempervivum in a rockery, with other plants that appreciate well-drained substrates. Here: Lewisia (photo JKehoe), Sempervivum soboliferum (photo Stephen Boisvert), Euphorbia myrsinites, and Phlox subulata ‘Emerald Cushion Blue’ (photo David J. Stang)

In combination with other small carpeting plants, Sempervivum can form a kind of miniature, original bed. Enjoy, for example, Acaenas and Azorella trifurcata! These are delightful plants with small leaves that will nicely cover the soil around Sempervivum.

To bring colour, choose plants with small, delicate flowers: carnations, aubrietas, pansies, Campanula muralis… Also discover Antennaria dioica, which bears cute small flowers in soft hues. Sempervivum also pairs very well with Lewisia cotyledon, which, like Sempervivum, forms basal, evergreen rosettes and produces splendid star-shaped flowers, often pink or orange.

Sempervivum also pairs well with navelwort, which usually grows spontaneously on rocks and walls.

Sedums and Sempervivum make a wonderful combination, as they are small, hardy, fleshy plants with the same growing requirements, and offer real diversity of forms and colours, changing through the seasons. Sedums can be yellow, bluish, green, reddish… It is very easy to combine them with Sempervivum, in pots or rockeries, to create an original little scene! We recommend, for example, Sedum ‘Angelina’, which offers a superb, very bright yellow and will bring contrast beside darker Sempervivum.

Use Sempervivum to create an alpine rockery, gathering plants that might be found naturally in mountains. Include, for example, gentians, saxifrages, Arenaria montana, edelweiss, lewisia, androsaces…

If you live in a region with a mild climate, where frost is rare, you can pair them with kalanchoes, cacti, euphorbias, opuntias… Favour succulents with fleshy leaves for an exotic-looking bed. Also discover the superb Aeonium arboreum and Crassula sarcocaulis, two shrubby, ramified succulents. Enjoy the graphic silhouette of agaves, notably the small Agave victoria-reginae, which offers handsome foliage marginate in white. You can also plant some yuccas. For this type of exotic bed, choose a warm, sunny spot in well-drained soil, preferably sheltered from wind.

You can also create a superb container composition, combining different Sempervivum varieties and adding sedums, for example. In a pot, you can place a trailing plant at the pot edge, such as Dichondra.

Do not hesitate to combine different species and varieties of Sempervivum to create striking effects of shape and colour! Let your creativity run free. Sempervivum offer such diversity that combinations seem endless.

Do not hesitate to combine different Sempervivum varieties, playing with shapes and colours. You can also add saxifrages and sedums. From left to right: Saxifraga paniculata, Sedum reflexum ‘Angelina’, and Sedum reflexum ‘Blue Spruce’ (photo Алина Кучерява)

Did you know?

• Medicinal virtues of houseleek

Houseleek Sempervivum tectorum has long been used for its properties. Juice contained in leaves is astringent and aids healing; it is effective against minor injuries, wounds, insect bites, burns… Leaves can be picked and applied directly, fresh, to wounds or inflammations.