Sempervivum arachnoideum ‘Cebenese’, commonly known as Cobweb Houseleek ‘Cebenese’, is a captivating succulent. It is celebrated for its distinctive “cobweb” appearance, created by fine, silvery filaments spanning its rosettes. Its resilience and striking features make it a popular choice for various garden settings. This cultivar is noted for its hardiness.
Distinguishing Features
The most striking characteristic of Sempervivum arachnoideum ‘Cebenese’ is its dense, white, web-like hairs that connect the tips of its leaves, giving it the common name “Cobweb Houseleek”. These delicate filaments cover compact rosettes, typically 2 to 4 inches in diameter. Leaves are often pale green, with reddish or pinkish tips in strong sunlight or cooler temperatures. This unique webbing can be so pronounced that it sometimes obscures the green foliage underneath, creating an almost stone-like appearance.
Cultivation and Care
Light Requirements
Sempervivum arachnoideum ‘Cebenese’ thrives in abundant sunlight, ideally receiving at least six hours of direct sun daily. While it tolerates partial shade, especially in hotter climates, more sun exposure intensifies the plant’s coloration and maintains its compact rosette form. Insufficient light can lead to etiolation, causing the plant to stretch and appear leggy. Providing optimal light ensures the plant develops its most vibrant hues and retains its characteristic tight growth.
Watering Practices
Due to its succulent nature, Sempervivum arachnoideum ‘Cebenese’ is highly drought-tolerant and stores water in its fleshy leaves. The most effective watering approach is the “soak and dry” method, allowing the soil to dry out completely between waterings. This means infrequent, deep watering during its active growing season. Overwatering or allowing the plant to sit in standing water can lead to root or crown rot. During the dormant winter months, watering should be significantly reduced or ceased entirely.
Soil Preferences
The correct growing medium is paramount for the health of Sempervivum arachnoideum ‘Cebenese’. This plant requires extremely well-draining soil to prevent waterlogging and rot. A gritty succulent or cactus mix is ideal, often amended with sand, gravel, perlite, or pumice for drainage.
Heavy, water-retentive soils, such as standard potting mixes, are unsuitable as they hold too much moisture around the roots. Adequate drainage, whether in pots with drainage holes or in garden beds, is essential for its longevity. A layer of gravel top dressing can also help prevent moisture from accumulating around the rosettes.
Temperature and Hardiness
Sempervivum arachnoideum ‘Cebenese’ exhibits remarkable cold hardiness, making it suitable for a wide range of climates. It is generally hardy in USDA Zones 4 through 10. This plant can withstand freezing temperatures and even survive under an insulating blanket of snow during winter. While tolerant of hot, dry conditions, it prefers average summer temperatures between 65°F and 75°F (18°C and 24°C). Its robust nature allows it to adapt to local conditions, including variations in heat, cold, and precipitation.
Fertilization
These plants are not heavy feeders and generally require minimal fertilization. If growth encouragement is desired, a very diluted, low-nitrogen fertilizer can be applied sparingly. Fertilization should only occur during the active growing season. Applying fertilizer during the plant’s dormant period in winter can weaken or harm it. Most healthy plants will thrive without any added nutrients, relying on the natural composition of their well-draining soil.
Propagation Methods
Propagating Sempervivum arachnoideum ‘Cebenese’ is straightforward, primarily through its prolific production of offsets, often called “chicks” or “pups”. These small rosettes form around the base of the mature “hen” plant on short stolons. To propagate, detach these offsets from the mother plant once they are a few inches tall and have developed roots. The separated offsets can then be replanted directly into well-draining soil. While propagation by seed is also possible, using offsets is the most common and easiest method, ensuring genetic replication of the parent plant.
Troubleshooting Common Problems
The most common issue encountered with Sempervivum arachnoideum ‘Cebenese’ is root or crown rot, almost exclusively caused by overwatering or inadequate soil drainage. Preventing this involves adhering to the ‘soak and dry’ watering method and ensuring the plant is in a highly porous, gritty soil mix. If the plant begins to stretch or become ‘leggy,’ this indicates insufficient light, a condition known as etiolation. Moving the plant to a brighter location with more direct sunlight helps it regain its compact form. Sempervivum arachnoideum ‘Cebenese’ is generally pest-resistant, but occasionally mealybugs or aphids can appear. These can be managed by wiping them off with a cotton swab dipped in rubbing alcohol.