About Sempervivum calcareum
Hailing from the sun-drenched, limestone slopes of the southern European Alps, particularly in France and Italy, the Sempervivum calcareum (often called the Stone Rose or Houseleek) is a true mountain treasure. It forms beautifully symmetrical, sculptural rosettes, typically growing 4 to 6 inches wide. Its plump, fleshy leaves boast a captivating color contrast. The base is a lovely blue-green or gray-green, while the sharp leaf tips proudly display a rich burgundy-red hue. You might notice these red tones deepening beautifully when your plant enjoys plenty of sunshine or cooler temperatures.
How to care for Sempervivum calcareum
Sun: Sempervivum calcareum will be happiest and show its best colors when it receives plenty of bright light. Aim for at least 6 hours of direct sunlight daily, whether outdoors or placed near a bright south-facing window indoors. Some gentle afternoon shade in very hot climates is appreciated.
Water: Like most succulents, this succulent plant prefers its soil to dry out completely between waterings. When you do water, give it a thorough drink, but then let the soil become dry again before the next watering. It's best to water the soil directly and avoid getting water sitting in the center of the rosette, as this can lead to rot. During the cooler winter months, you'll find it needs significantly less frequent watering.
Pot & Soil: Choosing a pot with a drainage hole is essential. A shallow, wide pot works well to accommodate the way it spreads by producing offsets (little "chicks"). Plant it in a fast-draining cactus or succulent mix. You can boost drainage even further by adding some perlite or pumice to the mix.
Fertilizer: Sempervivum calcareum is not a heavy feeder. To support its growth, you can give it a light feeding just once a year in early spring using a balanced fertilizer (like a 5-5-5 formula), diluted to half strength. Over-fertilizing can actually weaken its lovely, compact form.
Pests & Disease: The good news is that these plants are naturally quite resistant to pests. However, it's always wise to keep an occasional eye out for common succulent visitors like aphids or mealybugs. If you spot any, they can usually be managed gently with neem oil or insecticidal soap. Good air circulation around your plant also helps prevent any potential fungal issues.
Temperature Preferences: Sempervivium calcareum is incredibly tough when it comes to temperature! It thrives in cool to moderate conditions and is exceptionally cold-hardy, tolerating temperatures down to -20°F (-29°C) when planted in the ground (USDA zones 5-8). It loves summer temperatures between 65-75°F (18-24°C) but handles heat well if there's good airflow. In winter, it naturally goes semi-dormant, which is why it needs less water. The key for winter survival is keeping its roots dry in freezing temperatures – excellent drainage is essential.
Propagation: One of the joys of this plant is how easily it multiplies! It readily produces numerous offsets ("chicks") around the base of the mother plant. In spring or summer, you can gently twist or cut these little rosettes off (making sure they have some roots if possible) and pot them up to start new plants. While growing from seed is an option, it's a much slower process.
More Information
Primary color: blue-green
Secondary color: red
Cold hardiness: Zone 5a-8b (from -20°F to 20°F)
Product format: rooted in 2" nursery pot
Suitability: balcony, Window, Garden
Propagation: sidebuds
Special characteristic: low maintenance, slow-growing