Sempervivum arachnoideum
Sempervivum arachnoideum
Sempervivum arachnoideum, or cobweb houseleek, is a resilient succulent known for its unique cobweb-like appearance. Native to rocky regions of Europe, it thrives in well-draining soil and full sun, making it a popular choice for rock gardens and containers.
Everything it needs
9 essentials at a glance
Watering
Sempervivum arachnoideum, commonly known as cobweb houseleek, prefers to dry out between waterings.
Water thoroughly when the top inch of soil feels dry, typically every 2-3 weeks during the growing season. In winter, reduce watering to once a month. Signs of over-watering include mushy leaves and root rot, while under-watering may cause shriveled leaves.
Light
This plant thrives in full sun, requiring at least 6 hours of direct sunlight daily.
Ideal placement includes south or west-facing windows or outdoor gardens with ample sunlight. It can tolerate partial shade but may become leggy and lose its compact form.
Soil
Sempervivum arachnoideum prefers well-draining soil with a pH range of 6.0 to 7.0.
A cactus or succulent potting mix is recommended, or you can create your own by mixing regular potting soil with sand or perlite to enhance drainage.
Humidity
This succulent prefers low humidity levels, ideally below 40%.
To decrease humidity, ensure good air circulation and avoid misting. Signs of humidity stress include leaf rot and mold growth.
Temperature
The ideal temperature range for Sempervivum arachnoideum is between 65-75°F (18-24°C) during the day and slightly cooler at night.
It is hardy in USDA zones 3-10, tolerating cold temperatures down to -30°F (-34°C) but should be protected from extreme heat above 90°F (32°C).
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10 during the growing season, applying every 4-6 weeks.
In fall and winter, refrain from fertilizing. Signs of nutrient deficiency include stunted growth and pale leaves.
Pruning
Pruning is minimal but can be done to remove dead or damaged leaves.
Use clean, sharp scissors to cut away any unhealthy foliage. Deadheading is not necessary, as the plant will naturally shed old leaves.
Repotting
Repot Sempervivum arachnoideum every 2-3 years or when it outgrows its pot.
Choose a pot that is 1-2 inches larger in diameter. Signs it needs repotting include roots growing out of the drainage holes or stunted growth. To repot, gently remove the plant from its current pot, shake off excess soil, and place it in the new pot with fresh soil.
Propagation
Propagation can be done through offsets or leaf cuttings.
For offsets, gently remove the small rosettes from the parent plant and allow them to dry for a day before planting in well-draining soil. For leaf cuttings, take a healthy leaf, let it callous for a day, and then place it on soil, keeping it slightly moist until roots develop. The best time for propagation is in spring or early summer.
When it's unhappy
Yellow leaves
Why it happens
Over-watering or insufficient light.
How to fix it
Reduce watering frequency and ensure the plant receives adequate sunlight.
Leggy growth
Why it happens
Insufficient light exposure.
How to fix it
Move the plant to a brighter location with more direct sunlight.
Root rot
Why it happens
Poor drainage and over-watering.
How to fix it
Remove the plant from the pot, trim away affected roots, and repot in fresh, dry soil.
Leaf drop
Why it happens
Temperature fluctuations or stress.
How to fix it
Maintain consistent temperatures and avoid placing the plant in drafty areas.
Pests (e.g., mealybugs)
Why it happens
High humidity and poor air circulation.
How to fix it
Treat with insecticidal soap or neem oil and improve air circulation.
Care through the year
Spring
In spring, resume regular watering as the plant begins to grow actively. Fertilize every 4-6 weeks with a balanced fertilizer.
Summer
During summer, ensure the plant receives full sun and monitor for signs of dehydration, watering every 2-3 weeks as needed.
Fall
In fall, gradually reduce watering as the plant prepares for dormancy. Stop fertilizing by late fall.
Winter
In winter, water sparingly, about once a month, and keep the plant in a cool, dry location to prevent rot.
Toxicity & Safety
Sempervivum arachnoideum is non-toxic to pets and children. However, ingestion may cause mild gastrointestinal upset. It is always best to keep plants out of reach of pets and small children.
Good to know
How often should I water my Sempervivum arachnoideum?
Water your Sempervivum arachnoideum every 2-3 weeks, allowing the soil to dry out completely between waterings.
Why are my Sempervivum leaves turning yellow?
Yellow leaves are often a sign of over-watering or insufficient light. Adjust your watering schedule and ensure the plant receives enough sunlight.
What type of soil is best for Sempervivum arachnoideum?
A well-draining soil mix with a pH of 6.0 to 7.0 is ideal. A cactus or succulent potting mix works well, or you can create your own by mixing potting soil with sand or perlite.
Can I propagate Sempervivum arachnoideum from leaves?
Yes, you can propagate from leaves. Allow the leaf to callous for a day before placing it on soil, keeping it slightly moist until roots develop.
What temperature does Sempervivum arachnoideum prefer?
This plant thrives in temperatures between 65-75°F (18-24°C) during the day and can tolerate cold down to -30°F (-34°C).
How do I know when to repot my Sempervivum?
Repot when you see roots growing out of the drainage holes or if the plant's growth has stunted. Typically, this is every 2-3 years.
Is Sempervivum arachnoideum toxic to pets?
No, Sempervivum arachnoideum is non-toxic to both pets and children, making it a safe choice for households.
Grows well with
Track this plant in your garden.
Set care reminders, log growth, and join a community of plant lovers.