Sempervivum calcareum [sem-per-VEE-vum, kal-KAR-ee-um] is a succulent perennial native to the southern Alps in New Zealand and belongs to the Sempervivum plant genus and Crassulaceae (stonecrop) family.
It forms a large rosette of thick green leaves with reddish-purple tips.
Common names include:
- Old man and woman
- Roof houseleek
It’s also known as a hen-and-chicks plant, as it multiplies via offsets formed around the mother plant.
This is a hardy species, easy to cultivate and propagate, but specific care tips will help it thrive.
Sempervivum Calcareum Succulent Care
Size and Growth
The perennial houseleek grows a series of symmetrical densely packed rosettes with a dome-shaped appearance.
The thick succulent leaves are often blue-green or light green with reddish-purple tips at the pointed ends.
The plant starts with a single rosette, but short-stalked offsets eventually form a dense mat around the base plant.
Flowering and Fragrance
Sempervivum calcareum rarely flowers. It’s more common with older, mature plants after several years of growth.
If the plant flowers, the flowers typically appear in late summer.
The plant produces a cluster of yellow-eyed pale pink flowers on thick stalks with scale-like leaves. After the rosette flowers, it withers and dies.
Light and Temperature
Calcareum is frost tolerant and suited for outdoor growth in USDA hardiness zone 5a to 8b.
It can survive temperatures as low as -20° degrees Fahrenheit (-29° C).
Plant the houseleek under the partial sun to full sun. Place indoor plants near a window with at least eight hours of solid sunlight throughout the day.
Most of the growth occurs in the spring and summer.
During these seasons, the plant needs more shade from the afternoon sun.
If temperatures regularly exceed 80° degrees Fahrenheit (26° C), plant under partial shade instead of full sun.
To protect outdoor plants from freezing temperatures during the winter, insulate the plant with a blanket of packed snow or a loose pile of leaves.
Watering and Feeding
As a succulent, the houseleek is drought tolerant and does not need frequent watering. Overwatering increases the risk of fungal growth and root rot.
Wait until the top of the soil completely dries before watering the plant again.
When watering, avoid pouring water directly over the rosettes. Water the soil and the plant will send nutrients up through the root system to the leaves.
Soil and Transplanting
Use standard cactus or succulent potting mix.
To make cactus soil, combine one-part coir with two parts pumice and five parts regular potting soil.
This should offer even drainage.
When transplanting Sempervivum calcareum, it helps to let the plant dry overnight before replanting.
If possible, allow the soil in the current container to dry completely. This makes it easier to remove the plant without damaging the roots.
Carefully knock away as much soil as possible and then place it in a new container using a cactus mix.
No grooming needed, except for the removal of dead rosettes after flowering.
How to Propagate Houseleek Plant
Propagate the houseleek using cuttings or offsets.
Propagating with cuttings takes longer and doesn’t always produce satisfactory results.
To use cuttings:
- Cut a piece of a leaf at least a couple of inches long.
- Allow the cut to scab over, which typically takes one or two days.
- Plant the cutting in dry potting soil or cactus mix.
- Begin occasionally watering, allowing the soil to dry between each watering completely.
To propagate using offsets:
- Use a pair of gardening shears to cut away one or more offsets from the mother plant.
- First, dig away some of the dirt around the offset to reveal the thin stalk connecting it to the base plant.
- Cut the stalk and carefully remove the offset.
- Plant the offsets in individual containers and allow them to dry for one week before starting to water the plant.
Houseleek Plant Pest or Disease Problems
The houseleek is virtually disease-free and pest-free, but may occasionally suffer from rot due to overwatering or moisture conditions.
While the plant is incredibly winter hardy, in some regions, it may receive too much moisture from rain.
Adding more sand and pebbles to the soil helps improve drainage, reducing the risk of rot.
If the plant receives too much water and fungal growth appears, cut away the fungus and treat it with a fungicide.
Transplanting may also help.
When transplanting, replace the soil with something offering better drainage.
For severe fungal growth, the best option is often to discard the affected plants and save healthy offsets.
Another potential issue is scorching.
If the plant receives too much sunlight, the edges of the leaves may develop dark patches.
Move the plant to a shadier spot and allow it to heal or discard it and propagate the chicks.
Suggested Sempervivum Calcareum Uses
Due to its small size, the houseleek is best suited as an addition to rock gardens, cacti garden, succulent garden or a ground cover where it can bring more color to the display.
It’s also great as a stand-alone plant on a shelf or windowsill with plenty of filtered sunlight.