Sempervivum Arachnoideum Guide: How to Grow & Care for “Cobweb Houseleek”

Cobweb Houseleeks, also known as Cobweb Hens and Chicks are adorable hairy succulents that grow in clumps. At a first glance, one might think that these plants are covered in spider webs.

When you first notice Sempervivum Arachnoideum, it might seem like there is something straight out of a Halloween story infecting the plant because of all the white webs surrounding it. However, this fluffy succulent is quite harmless and looks great in any home or garden.

Sempervivum arachnoideum is a species of flowering succulents part of the family Crassulaceae. It originates from the Alps, Apennines, and Carpathian Mountains of Southern Europe.

These hardy succulent plants look amazing when grown in rock gardens, dry stone walls, and even in cracks in paving. If you don’t live in USDA hardiness zones 5a-8b, you might consider growing Cobweb Houseleek in containers.

As a fast-growing succulent, Sempervivum arachnoideum will soon take over the container by producing many offsets. This also provides a great opportunity for propagation. Due to their adaptable, easy-going nature, they are quite easy to grow and care for. However, there are a few things you must keep in mind if you want to grow Sempervivum arachnoideum.

Keep on reading to find out more.

About Cobweb Houseleek

• Cobweb Houseleek looks incredible in wintertime where there is nothing else of interest in your garden. During summer, tall, conical spikes of pink flower grow from the center of already mature plants.
• The name Sempervivum Arachnoideum [sem-per-VEE-vum, a-rak-NOY-dee-um] translates to always alive spider web.
• Cobweb Hens and Chicks are happiest when planted outdoors where they can get plenty of fresh air and sunlight. When grown in containers, make sure to take them out during warmer months to ensure they thrive.
• Sempervivum Arachnoideum succulents are hermaphroditic plants, meaning they have both male and female organs.
• The subspecies tomentosum has gained international recognition for its beauty and the Royal Horticultural Society’s Award of Garden Merit.
• Cobweb Houseleek has an interesting history. It was thoughts that those who owned one were protected against lightning and witches.
• Sempervivum Arachnoideum is not edible. However, if ingested it will not cause any harm to pets or humans. Ingesting a considerably large amount can cause vomiting, nausea, and diarrhea.

Cobweb Houseleek Features: An Overview

• Cobweb Houseleek succulents are low-growing plants with green rosettes covered in white fluff. These plants form clumps and spread by producing pups and offsets.
• The mother rosette, also known as the Hen, forms in a circular pattern and sends horizontal stems in every direction. From the stems, new rosettes called chicks or offsets emerge. Each chick forms its own root system and then detaches itself from the hen.
• Cobweb Houseleek is valued in cultivation for its ability to spread in hot, dry areas via offsets. This rosette-forming perennial will grow to be 3 inches (8 cm) tall and 12 inches (30 cm) wide.
• Although each tiny rosette is no more than ¾ inches (1.5 cm) wide, it is made out of more than 50 wedge-shaped leaves. These plants are grown mostly for their beautiful foliage and those who take good care of Sempervivum Arachnoideum will be rewarded with bright pink, star-shaped flowers in June and July.
• After flowering, the main plant will die. Many offsets are produced before this, and they can be used as replacements.
• This plant rarely blooms, especially when kept indoors, so you can expect it to be around for quite some time. After flowering has ceased, make sure to remove the dead plant from among the offsets.
• These plants are an excellent choice for those who want to create a green roof, as they are hardy succulents. Moreover, they are ideal for topiary, walls, or mosaics. Their fibrous and shallow root system is perfect for holding the soil in place even when planted vertically.

Growing Cobweb Houseleek

Cobweb Houseleek is a master of adaptation, meaning it can become perfectly adapted to most heat and cold conditions, including rain or snow. This plant thrives in full to partial shade, as long as it receives enough light every day. It grows best near south and west-facing locations, so keep that in mind when choosing a spot for planting.

Sempervivum Arachnoideum is a frost-hardy plant that can tolerate temperatures down to 23°F (5°C), as long as the soil is not very moist and doesn’t have compost. During very hot and dry weather, it is advised that potted Cobwebs are moved out of direct sunlight. When grown indoors, choose the brightest location, preferably near west or south-facing windows.

Poor lighting can cause your Sempervivum plants to die, so you might have to move them around the house a few times until you find the location where it’s happiest.

If your Cobweb Houseleek is not receiving enough light, you will notice it elongating or stretching out towards the window. This can cause slow or stunted growth, so make sure to increase the amount of light it receives. If your house receives poor lighting, you can consider using grow lights. This can help fulfill your plants’ lighting needs even during cold, dark winters.

Once your Cobweb Houseleek is established, it requires little to no grooming and maintenance. Moreover, it is resistant to most garden pests and diseases. Its biggest threats are root rot and vine weevil. Also, too much heat and food will lead to limp and stunted growth. Another great thing about planting Sempervivum Arachnoideum is that it attracts butterflies, so be prepared to welcome these colorful beauties in your garden.

Planting Cobweb Houseleek

Cobweb Houseleek is not very picky when it comes to location, as it can do well in rock walls, containers, and vertical gardens. If you want your Cobweb to thrive, make sure it gets 6 hours of sunlight every day. Plant in well-drained, sandy soil, and make sure the containers have drainage holes.

The soil they’re planted in is really important for these resilient succulents. The ideal soil pH should be somewhere between 6 to 8. Sempervivum is usually found growing atop mountains with rocky soil and high winds, so it dries out rapidly. During periods of drought, succulents have a chance to develop healthy, large root systems as they grow deeper to find water.

Sempervivum Arachnoideum, From Amazon

Even gardeners with the best intentions who keep the soil constantly moist for Cobweb Houseleeks can end up with a shallow root system and rotting leaves. Try using a top dressing to keep the leaves in top shape. Avoid heavy soils or low-lying beds that keep too much water. If you notice signs of distress such as mushy, translucent leaves it means that your plant might suffer from root rot.

When potting, use a compost specifically created for alpine plants, or create your own mix by adding 1/3 horticultural grit by volume. We recommend using a shallow, wide container where your Cobweb can easily spread.

Watering Cobweb Houseleek

Watering Cobweb Houseleek plants requires a little bit of finesse. The goal is to mimic their natural alpine conditions. Hardy succulents usually receive about 0.5″ to 1.0″ of water per week in their native habitat.

It’s recommended to water early in the morning or the evening to avoid the water evaporating or for the water droplets on the leaves to become like a magnifying glass and burn the plant. Even after long periods of drought, your Cobweb Houseleek can be revived. Start watering more frequently and deeply, giving the plant enough time to respond. You can water younger plants even twice a week to help them establish roots and grow faster.

During the winter, mature succulents don’t really need extra water from you. On the other hand, younger plants might need a bit of moisture to help them make it through. Dormant plants covered by a blanket of snow no longer need that much moisture. If you live in an area with cold, rainy winters without any snow, a plant cover is a good idea.

Propagating Cobweb Houseleek

Cobweb Houseleek can be propagated by seeds or root offsets. After the mother plant blooms and dies, you can easily propagate the chicks.  Spring is the ideal season for both methods. The easiest way to propagate Cobweb Houseleek is by root offsets. Simply detach them from the mother plant, making sure to leave enough roots so that they can proliferate. Next, repot them in a well-draining soil succulent mix and water them regularly.

In Conclusion

Cobweb Houseleek is an adorable hairy succulent that requires little care and can withstand even the snowiest of winters. Part of the family Crassulaceae, Sempervivum Arachnoideum is native to the Alps, Apennines, and Carpathian Mountains of Southern Europe. What we love most about this plant is that it can grow in rock gardens, green roofs, containers, walls, or mosaics.

Although it is a low-maintenance plant, Cobweb Houseleek is a bit fussy when it comes to lighting and watering requirements. It’s best to plant it in a sunny location and make sure the soil is fast-draining. Overwatering is more of a problem than not watering it too often. By keeping these simple tips in mind, you will have no trouble growing a beautiful and healthy Cobweb Houseleek plant.

Where are you keep your Cobweb Houseleek in winter: indoors or outdoors? Let us know in the comments below!