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

Description and botany

Sempervivum, or houseleeks, are succulent perennial plants that form rosettes made up of fleshy leaves. They are very low-growing, cushion- or mat-forming, the rosettes staying at ground level. They come mainly from the mountainous regions of southern and central Europe and western Asia. They number about 35 species and form a fairly diverse group. In addition, there are many horticultural varieties selected for their ornamental qualities… there are over 3,000, giving enormous diversity in shapes and colours. Houseleeks have been cultivated for a very long time. They were formerly planted on roofs and reputed to protect against lightning. Sempervivum tectorum is in fact called the “roof houseleek”.

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

Sempervivum montanum: botanical illustration

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

Houseleeks belong to the large family Crassulaceae, which gathers nearly 1,500 species. Sedums, Echeveria and Kalanchoe are also found in this family. They are mainly succulent plants, with fleshy, swollen tissues (leaves, branches or trunk serving as storage organs to hold water and minerals)… In fact, the name Crassulaceae comes from Latin “crassus”, meaning “thick, massive”! These plants are particularly adapted to life in very dry conditions.

Sempervivum are very close to the genus Jovibarba, but their flowers do not have the same shape (they are 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 that of Aeonium.

The name houseleek comes from the Latin Jovis barba, meaning “Jupiter’s beard”, because this plant was reputed 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. Also 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 give indications about morphology or habitat: S. montanum: “mountain houseleek”; S. arachnoideum: spider-web‑like; S. calcareum: calcareous houseleek; S. grandiflorum: large‑flowered, etc.

Houseleeks are very low plants, with rosettes remaining at ground level. They can be described as “stemless”: without a stem (in reality having a very reduced stem on which the leaves are attached). With their mat-forming habit, houseleeks follow the relief and shape of the rocks or rockeries where they grow. In general, they measure less than 10 cm in height, but gain a little height when in flower.

Houseleek rosettes take, in a way, the form of a small, flattened artichoke. Their size usually ranges between 2 and 10 cm in diameter. They are small in Sempervivum arachnoideum, not exceeding 3 cm in diameter, and much larger in Sempervivum ‘Commander Hay’. Rosettes are semelparous: they flower once and then die… however, each produces offsets that take over and replace it.

Houseleeks produce offsets, new rosettes borne on stolons (aerial stems). These grow gradually and root on contact with the soil. They may be carried some distance from the mother rosette or be very close, pressed against it. They allow the plant to spread, forming attractive mats, and to regenerate, since each rosette dies after flowering and is replaced by its offsets. Houseleeks can thus remain in place for a very long time in the garden because they renew regularly. The lifespan of a rosette is short, but that of a whole clump is very long. It is very easy to propagate houseleeks by dividing these rosettes.

Houseleek roots penetrate deeply, drawing water and minerals from far below the soil surface. They help anchor the houseleek firmly in the ground, making it suited even to unstable habitats (scree, rockeries…) or places with very little substrate. The houseleek “clings” to its support thanks to its deep roots, which can slip into fissures and gaps between stones.

Houseleeks have small fleshy, thick leaves arranged all around a small central stem. The fleshy nature of the leaves allows them to store water and minerals to resist drought, just like cacti and other succulent plants.

The leaves are inserted in a helicoid fashion, forming a spiral when looking at the rosette from above. Houseleeks are plants with exceptional graphic appeal, evoking a superb rosette. Generally, the leaves are inserted rather densely (probably reducing water loss by evapotranspiration and better insulating the plant against extreme temperatures). This character is strongly marked in Sempervivum ciliosum, which forms small globular rosettes, well rounded with very imbricate leaves. Likewise, rosettes of Sempervivum globiferum take the shape of small, very rounded spheres. They are original and fun.

Houseleeks offer great diversity in their foliage, both in shape and colour. Leaves can be quite narrow and long, or rather flat and broad. They generally measure between 0.5 and 5 cm in length and may be spatulate, oblong, obovate… They are often tapered at the tip, ending in a point. Leaf shape is very striking in the variety ‘Grigg Surprise’: leaves are elongated, rounded in cross-section, and curved into a “claw” at the tip.

They often take reddish, purplish or bronze hues… Hybridization has produced thousands of varieties with the most diverse shades. Rosettes of the variety ‘Alpha’ are purplish – deep red, contrasted by the white cilia that highlight the lamina edge. Those of ‘Chick Charms Gold Nugget’ are impressive with their bright yellow‑orange hue. ‘Cherry Berry’ shows a lovely red tone, and ‘Dark Beauty’ is very dark purple, almost black. In general, leaves are often tipped with a reddish point (this is very visible in Sempervivum calcareum!). Leaves can also be bluish, as in ‘Pacific Blue Ice’; and even yellow: ‘Cmiral’s Yellow’! This last variety is ideal for bringing brightness and playing with colours, for example when paired with sedums of varied tones.

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

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

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

In Sempervivum arachnoideum, the centre of the rosette is covered with many fine white threads, resembling a spider’s web… hence its name. Likewise, in Sempervivum ‘Boule de Neige’, rosettes take the form of white balls covered in fine white threads. These houseleeks have a very soft aspect. Sometimes houseleek leaves are ciliate along the lamina edge, producing a superb effect like frost. The hairs gleam in the sun. Leaves can be glaucous, as in Sempervivum ‘Othello’.

Houseleek rosettes are of course evergreen. They remain present all year long, summer and winter!

Houseleeks take several years, often between two and four, to flower. 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 in height. It really appears as an extension of the rosette, which suddenly grows upwards. The floral stem is covered in leaves (or scales) resembling those of the rosette. It is slightly ramified at the top, where the flowers are gathered in a paniculate cyme.

Houseleeks bear beautiful star-shaped flowers, quite original. They have a refined, delicate aspect with many details due to the numerous floral parts. Flowers often have between 8 and 15 petals, and usually an even higher number of stamens. Petals are fairly thin and radiating, giving a star shape. They surround a ring of stamens arranged circularly. Flowers are hermaphrodite, bearing both male and female organs. However, stamens open before the pistil, which helps avoid self-fertilization.

Flowers are generally pink, red or yellow… often with a muted tone, not very bright but rather soft, for example pale pink tending to brown, pale yellow, pinkish white or greenish… They are a nice pink in Sempervivum arachnoideum, yellow in Sempervivum ciliosum… Petals often have a darker median line, adding detail and contrast to the flower.

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

Houseleek flowering: 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 and release the many tiny brown seeds they contain. It is possible to collect and sow them, but it is much simpler to propagate these plants by division. As rosettes are semelparous, they die after producing seeds.

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

Main Sempervivum varieties

Most popular varieties

Our favourite varieties

Other varieties to discover

Sempervivum arachnoideum

This houseleek produces rosettes with fairly rounded shapes, notable for being covered with very fine white threads resembling cobwebs. It bears lovely pink flowers. It has received the Award of Garden Merit from the Royal Horticultural Society (RHS).

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

See the product sheet

Sempervivum Othello

This superb houseleek variety has rosettes green at the centre and rather red towards the outside, with outer leaves well spreading and elongated. It has received the Award of Garden Merit from 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 it is naturally found in France. It forms elegant rosettes composed of fairly broad, tapered leaves. Leaves are green and end in a reddish point, which gracefully emphasises their shape. It has received the Award of Garden Merit from 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. Its leaves are green in summer and become 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

This superb variety generally bears reddish leaves with green tips. Its hue evolves over time, offering a beautiful 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 highlighting the plant’s rosette form.

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

See the product sheet

Sempervivum ciliosum var. borisii

This charming variety forms globular rosettes composed of numerous small imbricated 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 autumn, while becoming rather green again in autumn and winter. Its rosettes are particularly elegant, composed of numerous imbricated leaves forming a superb rosette. It also bears 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, purplish and almost black. It is ideal for creating contrast effects alongside lighter-coloured plants, and allows design of 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 rather dark hue, oscillating between purplish-red and dark green, with some bluish nuances. Its colour is therefore quite unique! Its leaves are fringed 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 Sempervivum in full sun, as they need plenty of light. However, although they are fairly resilient and adapted to drought, Sempervivum do not like very high temperatures. If you live in a Mediterranean area, it is preferable to place them in partial shade for some protection. In other regions, place them in full sun.

They thrive on rocky or stony, well-draining soils. 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 time. Also consider planting on a mound or slope so water can drain away easily.

Sempervivum can grow on very poor ground and require only a small amount of substrate. Thus, they can be installed on an old stone wall, in fissures… 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 an arrangement in a pot or trough, for example with sedums and other small plants. Sempervivum make it possible to green spaces where other plants would struggle to grow. You can easily grow them even without a garden… a simple windowsill is enough! As they need little soil or maintenance, Sempervivum can be placed on any kind of support or object, in bowls, troughs, pottery, suspended in an improvised pot…

As Sempervivum are mountain plants, they are very hardy and can be grown even in fairly cold regions without needing winter protection. The only precaution concerns excess moisture. If you live in a rainy region, they may need shelter in winter, protected from rain and stagnant humidity… 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 all available space is occupied. They fill the available space well.

As Sempervivum are small plants, to showcase them it is better 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 place them in a pot or arrangement positioned, for example, on a table on your terrace, or if you plant them in the crevices of a wall, rather than placing them at ground level in a conventional bed.

Sempervivum 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 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 open ground:

1. Start by preparing the site. You can create a rockery using stones, gravel… Ideally, we suggest planting on a mound or slope so that water can drain away rather than be retained. In all cases, 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. Remove the Sempervivum from its pot and plant it.
4. Replace soil around it.
5. You can optionally lay a layer of small gravel on the surface around the rosette, as this prevents water from stagnating at the collar and limits weed growth.
6. Water lightly.

Generally there is no need to continue watering; rainwater should be sufficient to meet the plant’s modest needs.

→ Read also: How to plant succulents in open ground in the garden?

For planting in a pot:

1. Choose a container, preferably with drainage holes, and place a layer of gravel in the bottom to facilitate water 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 Sempervivum.
4. You can add a layer of small stones on the surface of the pot to prevent water pooling at the collar.
5. Place the pot in full sun (or in partial shade if you live in the south of France).

For winter, you can move it to a location sheltered from 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 Sempervivum has a minimum amount of substrate in which to establish itself.

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

Care

Once established, Sempervivums need almost no maintenance. These are hardy plants, tolerant of both cold and drought. In general, rainwater is sufficient to meet their water needs. You can, however, water them occasionally during dry spells, but avoid excess moisture. Likewise, Sempervivums do well in poor soil and do not require fertiliser.

Tidy clumps occasionally, remove spent flowers, cut away damaged parts, divide rosettes, and remove material that could cover them: dead leaves in autumn, plant debris, other plants growing nearby… Sempervivums should be kept in full sun. Don’t hesitate to prune surrounding plants to prevent them shading the Sempervivums. Similarly, as rosettes die after flowering, you can remove those that have dried up. We also recommend dividing them from time to time to rejuvenate them and give them more room to develop.

Regarding diseases, Sempervivums can be affected by rust (Endophyllum sempervivi), which appears when moisture is stagnant. It is a fungus parasitic on 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 reduce watering and improve drainage if necessary.

In any case, the main cultivation problem you may encounter with Sempervivums is excess moisture. It is therefore important to plant them in a well-draining substrate. Likewise, placing gravel around rosettes prevents water from pooling and causing them to rot. 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 shelter against rain. Pubescent, silky varieties are more sensitive to winter moisture than others.

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 easy to divide! Each houseleek rosette gives rise to new rosettes, right next to the original, or attached to a stolon. Simply separate them. Best done in spring, around April. Ideally wait until the offset has produced some roots and the stolon begins to wither and die back. However, they multiply easily even without this.

1. Find 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 callus).
4. Replant them, in pots or in the ground, in a well-draining substrate (mix of potting compost and sand).
5. Water lightly.

Over time, the rosettes will grow and in turn produce new offsets.

Use and companion planting in the garden

Obviously, you can easily plant sempervivums in a rockery or on a low wall (even on a green roof), with other small plants that accept growing 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 with 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 mat-forming habit.

Place sempervivums at front of a rockery, and plant slightly larger specimens behind them, which will bring volume: yarrow, lavender, agave, cistus, phormium, phlomis… Avoid placing them too close so they do not smother or shade each other. Do not hesitate to also include some ornamental grasses (Carex comans, blue fescue, Lagurus ovatus…), for the graphic effect and lightness they provide! You can even plant small rockery ferns, such as Cheilanthes lanosa or Asplenium ceterach.

You can perfectly well install sempervivums 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 association with other small groundcover plants, sempervivums can create a sort of original miniature bed. Enjoy, for example, Acaenas, and Azorella trifurcata! These are charming small-leaved plants that will nicely cover soil around sempervivums.

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

Sempervivums also go well with navelwort, which usually grows spontaneously on rocks and walls.

Sedums and sempervivums are a marvellous combination, as both are small, hardy, fleshy plants with the same cultural requirements, and they offer real diversity of forms and colours, changing through the seasons. Sedums can be yellow, bluish, green, reddish… They are very easy to pair with sempervivums, in pots or rockeries, to create an original little scene! We recommend, for example, sedum ‘Angelina’, which offers a superb, very luminous yellow and will provide contrast beside darker sempervivums.

Use sempervivums to create an alpine rockery, gathering plants you might naturally find in mountains. Integrate, 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, which will give your bed an exotic look. Also discover superb Aeonium arboreum and Crassula sarcocaulis, two succulents with a shrubby, ramified habit. Enjoy graphic silhouette of agaves, notably small Agave victoria-reginae, which offers beautiful foliage marginate with white. You can also plant a few yuccas. To create 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 varieties of sempervivums and adding sedums, for example. In a pot, you can place a trailing plant on outer rim, such as Dichondra.

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

Do not hesitate to combine different varieties of sempervivums, playing with shapes and colours. You can also add saxifrages and sedums. In order, at 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 stings, burns… Leaves can be picked and applied directly, fresh, to wounds or inflammations.