Sempervivum Calcareum, commonly known as Calcareous Houseleek, is a succulent plant species belonging to the Crassulaceae family. It is native to the mountainous regions of Europe, specifically the Pyrenees, the Alps, and the Balkans. Its name is derived from the Latin words "semper" (always) and "vivus" (living), which refer to its ability to survive in harsh conditions. The species name "calcareum" refers to the plant's preference for calcareous or limestone-rich soil.
This plant boasts a striking appearance, with rosettes of plump, juicy leaves arranged in a circular pattern around the center. These leaves typically sport a green or blue-green hue with tips that flush red, reaching up to 3-4 inches in diameter. Rosettes sit low to the ground, topping out at a height of up to 4 inches. In late spring or early summer, small, star-shaped flowers bloom in shades of pink or red.
Sempervivum Calcareum is a robust and drought-tolerant plant, thriving in harsh weather conditions. It's a favorite amongst gardeners for its minimal upkeep and striking appearance. This plant is an ideal choice for those seeking an eye-catching, low-maintenance addition to their rock garden, especially in dry and arid regions.
Toxicity
Sempervivum Calcareum is not considered toxic to humans or pets. The plant is generally safe to handle and touch, and there are no known reports of significant toxicity or harmful effects associated with its consumption. However, like with any plant, it is important to practice caution and keep it out of reach of children and pets to prevent accidental ingestion or allergic reactions.
General Care
Light
Sempervivum Calcareum plants are sun-loving succulents that can thrive in a range of lighting conditions, from full sun to partial shade. They require a minimum of 6 hours of direct sunlight daily to grow and develop optimally. In their native mountainous habitat, they are accustomed to extended exposure to direct sunlight but can also tolerate some shade.
Sempervivum Calcareum plants are sun-loving succulents
For indoor Sempervivum Calcareum, position the plant near a bright and sunny window where it can bask in plenty of natural light. If the plant receives insufficient light, it may become elongated and spindly, with slender leaves and a less robust structure. On the other hand, overexposure to direct sunlight can result in a reddish or brownish coloration and sunburn. It is therefore essential to maintain a balance between adequate light exposure and shielding the plant from excessive heat and direct sun.
Watering
Sempervivum Calcareum is drought-tolerant and should be watered sparingly. For indoor potted Calcareum, you should only water this plant when the soil is completely dry to the touch and drain all excess water to prevent root rot. For outdoor Sempervivum, it will typically receive sufficient moisture from occasional rainfall, especially in regions with moderate to high rainfall. However, in regions with little rainfall or extended dry periods, it may be necessary to supplement rainfall with occasional watering. You should use only distilled water or rainwater, as tap water may be too harsh and can burn the roots.
Soil and Fertilizer
Sempervivum Calcareum flourishes in sandy, well-draining soil that is slightly acidic to neutral in pHs. To prevent waterlogging and improve soil aeration, it's best to use a soil mix that contains a high proportion of sand or perlite. You can use any high-quality cacti soil mix, or make your own soil using 1 part regular potting soil, 1 part coarse sand or perlite, and 1 part pumice or lava rock.
As a low-maintenance plant, Sempervivum Calcareum does not require frequent fertilization, if at all. It can thrive in soil that is not very nutrient-rich. However, adding a slow-release fertilizer to the soil mix once or twice a year during the growing season (spring and summer) can help to support healthy growth and strong root development. Be cautious not to over-fertilize, as this can lead to a buildup of salt in the soil that can harm the plant's roots.
Temperature and Humidity
Sempervivum Calcareum can tolerate a wide range of temperatures. This plant is a cold-hardy succulent and can grow outdoors in USDA hardiness zones 5a to 8b. This means it can survive in areas where temperatures can drop as low as -20°F in winter. It also grows well in most indoor environments with temperatures between 60-85°F.
In terms of humidity, Sempervivum Calcareum is adapted to low-humidity environments and can tolerate dry air. It can even grow in arid conditions with minimal rainfall. High humidity levels can lead to fungal diseases and root rot, so it's best to avoid placing the plant in areas with high moisture levels (over 50%) or stagnant air, like in a bathroom or kitchen. If your room is too humid, you can increase airflow by opening the windows regularly or using a dehumidifier.
Potting and Repotting
Sempervivum Calcareum can be grown in containers or planted directly in the ground. You just need to make sure that the soil is well-draining, and the environment has good airflow. Good drainage is extremely important for all succulents. For potted Sempervivums, a pot made from a porous material like concrete, terracotta, or ceramic is recommended. The pot also needs at least one drainage hole.
Sempervivum Calcareum is a slow-growing plant that doesn't require frequent repotting. It's recommended to repot Sempervivum Calcareum once every 2-3 years, or when the plant has outgrown its current container. Repotting can be done in the spring or summer when the plant is actively growing. Gently remove the plant from its current container, loosen the root ball, and plant it in a new container just one size bigger with fresh soil mix.
Pruning
Sempervivum Calcareum does not require regular pruning, as it naturally grows in a compact, rosette shape. However, if you notice any dead or damaged leaves, you can carefully remove them from the plant using a pair of sterilized scissors or pruning shears. It's important to sterilize your tools before use to prevent the spread of disease or pests. You can also prune off flower stalks that appear on the plant, as this can divert the plant's energy away from growing and maintaining its rosette.
Propagation
Sempervivum Calcareum propagation is very easy with offsets, or baby plants that grow around the parent plants in the growing season (spring-summer). You should wait for the offsets to mature and develop their own set of roots and reach around ½ of a mature plant’s size before separating them from the mother plant. This usually takes around 2-3 months. Gently remove the baby plants using a sharp, clean knife or scissors. Make sure to cut as close to the base of the offset as possible to avoid damaging the mother plant. Plant these tiny beauties in their own pots or garden area with moistened soil. Keep baby plants in a bright, well-ventilated place and protect them from direct sunlight. During the first few weeks, it's important to keep the soil moist but not waterlogged, as excess moisture can lead to rotting.
Common Problems
Sempervivum Calcareum is a hardy and disease-resistant plant. It doesn’t get bacterial or fungal infections easily, but it can still be susceptible to certain problems.
- One common issue is overwatering, which can lead to root rot and fungal diseases. To prevent this, make sure to allow the soil to dry out between watering sessions, and avoid getting water on the leaves or center of the rosettes.
- For both indoor and outdoor plants, pests, such as mealybugs, aphids and spider mites, can infest the leaves and cause damage. Regularly inspect the plant for signs of pests, such as webs or sticky residue on the leaves, and treat them with insecticidal soap or neem oil solution if necessary.
- For outdoor plants, although Sempervivum Calcareum isn’t a preferred food source for outdoor animals such as deer, rabbits, and squirrels, but in some cases, animals may still nibble on the leaves or flowers, particularly if food sources are scarce. You should use fences around your garden to protect your plants.
- Sempervivum Calcareum can be prone to sunburn if exposed to direct sunlight for too long, leading to discoloration and damage to the leaves. To prevent this, provide the plant with some shade during the hottest parts of the day, especially in areas with intense sunlight.
