Common houseleek: where it grows, plant care & winter hardiness
Common houseleeks do not only look beautiful. They are also extremely easy to care for and cope well, even in extreme periods of drought.
Common houseleeks (Sempervivum tectorum) are probably the best known and most commonly found species of houseleek in gardens. They are characterised by their great hardiness, rather large, uniform rosettes and rapid growth, thanks to which they quickly cover their place of planting with a handsome, low cushion.
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Common houseleek: flowering time, origin and characteristics
Common houseleeks are succulents in the stonecrop family (Crassulaceae). This means they can cope with extreme drought because they store water in their leaves for long periods and have also decisively adapted their energy metabolism to desert-like conditions. However, their home is not in a desert, as one might assume, but here in Europe. It is found naturally in many mountains such as the Alps or the Caucasus in rocky, dry and sunny locations.
As evergreen perennials, common houseleeks are hardy and form leaf rosettes 4 to 15 inches in diameter. The size depends on the location and nutrient supply. The larger this turns out, the larger will be the rosettes. The leaf colour depends on the variety, site conditions and season, but in most cases is green to reddish-brown.
Common houseleeks do not bloom annually, but only after they have grown as a rosette for several years. Then the shoot with the leaves begins to stretch up, usually 10 to 30 cm, rarely 50 cm. At its top between July and August appear the often pink-red star-shaped flowers. With the flowering at the same time ends the life of a rosette, because after it dies and withers.
But this does not mean that the whole plant is lost. Common houseleeks reproduce independently via offshoots. Thus, they themselves form small daughter rosettes, which begin to grow in the vicinity of the original rosette. If a rosette blooms and then dies, there are still enough others that continue to grow, bloom and multiply.
What is the difference between common houseleeks and houseleek? The genus of houseleeks (Sempervivum) includes about 60 species of houseleeks. The common houseleeks is just one of them. So even though the two names sound very similar, houseleek means the whole genus Sempervivum and roofleek means only the species Sempervivum tectorum.
The most beautiful varieties of common houseleek
The number of cultivated varieties of common houseleeks is almost unmanageable. This is due to the fact that common houseleeks are intensively bred by special breeders and collectors and cultivated with a wide variety of leaf and flower colouration. The varieties presented here are usually readily available in stores and suitable for amateur gardeners.
- ‘Atroviolaceum’: The old variety was first mentioned as early as 1929. Its distinctive features are large rosettes and leaves that turn from green to red-purple.
- ‘Metallicum Giganteum’: ‘Metallicum Giganteum’ is a variety that forms very large rosettes. Leaf colouration ranges from green to metallic red-brown.
- ‘Othello’: ‘Othello’ is a red common houseleek. Although the leaves are usually not deep red throughout the year, but at times green.
- ‘Noir’: ‘Noir’ is a hybrid roofroot characterised by green leaves with distinctly darker, rather reddish leaf tips. The red flowers are also eye-catching at flowering time.
Planting common houseleek: location and procedure
Common houseleeks thrive, in the experience of perennial gardeners, in stone plants, stone joints, wall crowns or in alpine gardens. Also in nature, roofroot is usually found in full sun, dry, warm and rocky locations. Shade, moisture and normal garden soil, on the contrary, do not like common houseleeks at all. These conditions must be achieved in the garden as much as possible. Therefore, Common houseleeks are particularly suitable as rock garden plants or for greening roofs. However, you can just as well plant common houseleeks in bowls or keep them indoors. For even more ideas on planters for common houseleeks, as well as some suitable planting partners, see our article on planting and caring for Houseleeks.
What soil is suitable for common houseleeks?
Sempervivum tectorum prefers a very permeable, rather acidic substrate. Common houseleekss also grow well in very nutrient-poor substrates, thank a greater supply of nutrients but with larger rosettes. These requirements can be met, for example, by mixing our Plantura All Purpose Compost with expanded clay or gravel in a 1:1 ratio. Our soil is peat-free and consists of 100% natural ingredients. As a result, around 60% less CO2 is emitted during their production compared with conventional potting soils. Alternatively, you can use high-quality succulent soil.
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How to go about planting common houseleek
- If the plant that you purchased, already has several rosettes, you can safely separate them before planting and plant separately. This not only saves money, the seedlings have enough space and areas are overgrown faster.
- Before planting the roof root should ensure that water can drain down well. In planters and normal garden soil, this is achieved by adding a drainage layer at depth. For example, it can be made of pebbles, shards of clay or grit and may fill your planter well up to half.
- The drainage layer is followed by your coarse planting substrate, which should be slightly moistened, but in any case not wet.
- Now cover the surface of the bed with stones over a large area, and then plant the common houseleeks. Keep a planting distance of about 20 cm and prefer to place the rosettes a little higher. The upper layer of stone reduces the likelihood that the lower leaves begin to rot.
Tip: If you are planting your rooflower on stone, planting usually just means laying it flat in a depression filled with some substrate and pressing down lightly.
The right care
If common houseleeks feel comfortable in your location, roof root care is kept to a minimum. Watering them is usually not necessary, even during periods of extreme drought. Only in the pot it is part of the proper care of common houseleeks at regular intervals. However, do not water until the soil feels dry even 1 cm below the surface.
Sempervivum tectorum is one of the few houseleek species that is a bit more nutrient hungry. Thus, the care of common houseleeks may include annual fertilisation. The best time for this is in the spring. Be sure to use a slow-release fertiliser that meets the increased potassium needs of Common houseleeks. This applies, for example, to our Plantura Tomato Food. It is additionally 100% free of animal products and harmless to pets and garden animals.
Since the rosettes of roofroot after flowering die and no longer look beautiful, faded rosettes can be easily removed. It is important to have allowed the formation of daughter rosettes before flowering, so that the plant continues to serve the garden.
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Is the common houseleek hardy?
Since they can tolerate temperatures down to -34°C, common houseleeks are very hardy.
Problems can arise only in wet winters, because in wet conditions the leaves of common houseleeks quickly begin to rot. For this reason, make sure that common houseleeks do not collect water in trays and pots, and that houseleeks in the garden have good drainage.
Propagating common houseleeks
Propagation of common houseleeks can be done both by cuttings and seeds. The way via offshoots is much easier. If you are still interested in propagating common houseleeks from seed, you can find the exact procedure in our overview article on houseleeks.
If common houseleeks are propagated via offshoots, the daughter rosettes are genetic clones of the mother rosette. So they will look almost the same. The best time to propagate via cuttings is in the spring. However, it is possible into the fall.
- Prepare the new location for your rooflower offshoot as described above.
- Carefully separate one leaf rosette from the rest by pulling them apart with your fingers. A sterile knife can also be used to cut through connecting pieces of shoots and roots.
- Try to pull out as many roots as possible with the offshoot. This will make it easier for the rooflower offshoot to grow later. But do not worry if your offshoot has retained only a few roots. Common houseleeks are capable of forming new root systems relatively quickly.
- Plant the cutting in its new location and water it lightly. Make sure that the rosette is not too deep, but preferably on a layer of stones.
Toxicity and use as a medicinal plant
In principle, common houseleeks are classified as non-toxic. This applies to both humans and animals. However, as with anything, excessive consumption can lead to symptoms of poisoning such as nausea and vomiting.
Common houseleeks have long been cultivated as a medicinal plant. They are also the most scientifically studied Sempervivum species. Thus, some healing effects of common houseleeks could be proven in studies. The effects of roofroot may include analgesic, antioxidant or anti-inflammatory. Usually Sempervivum but is used only externally, for example, in ointments or by applying the sap to affected areas.
A perennial that can also be cultivated as a medicinal plant and is drought tolerant is betony (Stachys officinalis). It needs a little more water than common houseleek, but blooms annually and can also be used to dye fabrics.
