Sempervivum is a genus of some 40 species of perennial, evergreen plants that originate from a diverse range of environments. There are sempervivums native to Alps, the Carpathians but also the Sahara and other dry or stony places.
Sempervivums are also nicknamed houseleeks which is a bit of a misleading name considering that they are not related to the onion family, which the actual leek is part of. But could this nickname stem from sempervivums being good house plants?
Unfortunately no. Sempervivums are not suitable to be grown indoors and in the majority of cases will first stretch towards the closest source of light and then eventually die.
We have personally tried growing at least 4 different Sempervivum species indoors in a variety of positions including a sunny windowsill that would get about 3 hours of sun, but every time the plants would stretch from the middle and then die within 3 or so months (some sooner). This personal experience is backed up by some of our customers.
The only time we think Sempervivums could be grown inside is if they were in a sunroom, an exceptionally bright windowsill with over 5 hours of sun (this would have to be quite a long window) or with a help of a growing light.
So what to do with sempervivums and how to care for them?
The best place for these pretty and hardy plants is the great outdoors. Although sempervivums are not that crash hot about full sun during summer (here in Australia they struggle being in full sun when temperatures start climbing north of 35C/95F) they will happily live through heatwaves as long as they are protected from direct sun on very hot days. Because of their vulnerability to extreme sun, it might be a good idea planting them in a partly shaded position, in climates with hot summers. Many Sempervivums, unlike the great majority of succulents, are frost hardy and should survive frost and snow in winter. We would recommend double checking your particular species if the plan is to leave them outdoors during freezing winters.
Due to their flat growth habit, sempervivums are a great choice for all sorts of succulent crafts. They can be used to make succulent wreaths, walls, frames, animals etc. The key to keeping them alive with not much potting mix is to water frequently and not leave dry for too long. The plants should also not be exposed to hot sun and be kept in partial shade, especially in summer.
Sempervivums grow best planted in the ground due to their ever-spreading habit but they will also tolerate pots. As they begin to clump and form a mat of rosettes, it helps if they are re-potted into a bigger pot every year. This will ensure more growth and healthier rosettes.
In the ground, Sempervivums tolerate even very poor soils but will grow faster and bigger if a bit of good quality potting mix is mixed through the soil. In pots a good quality all rounder or succulent potting mix should be used. Never use garden soil in pots as this is likely to stunt the growth or kill your plants.
Sempervivums do not seem to mind the water and are unlikely to rot if left exposed to rain. In fact they seem to like regular watering. Although they will survive periods of drought, they are unlikely to grow well and the rosettes will remain quite small when water is withheld. The best advice for watering is to let the potting mix dry out between waterings, though do not panic if the plants are exposed to days long rain. They are unlikely to fall prey to rot.
Sempervivums are extremely easy to propagate from pups. One rosette can produce dozens of little pups/chicks/offsets that are easy to pull off and pot up.
Sempervivum pups also roots quite fast and have a very good success rate. The most important thing is to keep the little pups out of harsh sun (in filtered light or under shade-cloth) and water regularly when the potting mix dries out.
Leaf propagation is not possible for Sempervivums. These plants also do not flower very often, making seeds scarce, but according to various articles online, Sempervivums can indeed be propagated by seed. Just like with many succulents, it is likely to take at least a year or two (best case scenario) before the seed grows into a decent size rosette.
Sempervivums are very susceptible to the dreaded mealy bug. They can attack both foliage and the roots. The good news is that Sempervivums looks are not likely to be distorted and marked as much as in other succulents due to their toughened leaves unless the infestation is quite severe. Having said that mealy bugs need to be nipped in the bud as soon as possible as they can spread to other plants quickly. If there is only a couple squashing them with a toothpick is very effective. In an infestation with multiple mealies pour 70% isopropyl alcohol all over the plant. Pesticides may or may not work- we found they more often don’t as mealy bugs can grow resistance.
Another little bugger that likes to attack Sempervivums is the Aphid. Aphids are little black, green or brown bugs (they can come in other colours too) and sometimes seem to appear overnight. Some aphids also have wings and attack en-masse. They can easily be killed by Pyrethrum based sprays though.
Not much more bothers these plants. The occasional slug or a caterpillar can take a chunk out, but it does not happen very often.
Sempervivums are listed as non-toxic to humans and pets, though as with the majority of succulents, we do not recommend eating them. Despite the nick name ‘houseleek’ these guys are not meant to be cooked up or tossed in salads.
In conclusion, if you’re after an indoor succulent Sempervivum is not the best choice. They are outstanding and attractive garden plants and that’s where they should be enjoyed. If you’re after indoor succulents that do not mind being in shade have a read through this article.
If you’ve successfully grown Sempervivums indoors and have some good tips for our readers, you can comment below 🙂