The Tree Aeonium (Aeonium arboreum) is a striking succulent native to the Canary Islands. Its architectural form features thick, branching stems topped with large, symmetrical rosettes of fleshy leaves, earning it the common name Tree Houseleek. This shrub-like appearance makes it a popular choice for Mediterranean or dry-climate gardens. Successful cultivation requires understanding its unique growth cycle and specific environmental preferences.
Establishing Your Tree Aeonium
Proper substrate preparation is essential for establishing a Tree Aeonium. Like most succulents, this plant is susceptible to root rot, requiring a growing medium with exceptional drainage. A good mixture consists of standard potting mix blended with gritty amendments, such as pumice, perlite, or coarse sand. Aim for a ratio of approximately 50% organic material to 50% inorganic grit to ensure quick water movement.
Tree Aeoniums are typically grown outdoors in USDA hardiness zones 9 through 11, tolerating minimum temperatures around 25°F to 30°F. In colder regions, container planting allows the plant to be moved indoors for winter protection. When planting, set the root ball at the same depth it was previously growing. Withhold significant watering for the first few days after planting to allow any damaged roots time to heal.
Routine Care: Light, Water, and Temperature Needs
Light Requirements
Tree Aeoniums thrive in bright light, which maintains their compact rosette shape and vibrant foliage color. In cooler coastal climates, the plant tolerates full sun exposure. However, in hot inland areas, it benefits from partial shade, especially during intense afternoon heat. Insufficient light causes etiolation, where stems stretch out and become leggy as the plant searches for a stronger light source.
Watering and Feeding
Watering should follow the “soak and dry” method: thoroughly saturate the soil and then allow it to dry completely before watering again. Watering frequency changes seasonally because the active growth phase is not during the summer. During peak growth in winter and spring, watering is required more frequently than in the dormant summer months. Since Tree Aeoniums are adapted to nutrient-poor soil, they do not require heavy feeding; a half-strength balanced fertilizer applied once or twice during the winter growing season is sufficient.
Temperature Management
Temperature management is important for this subtropical plant due to its low tolerance for cold. While mature plants can briefly handle temperatures down to freezing, extended exposure below 40°F (4°C) should be avoided as it causes significant damage. Container-grown plants must be relocated to a sheltered location, such as a garage or bright window indoors, when freezing temperatures are imminent. High heat is also a factor, as temperatures above 80°F often trigger the plant’s summer dormancy period.
Seasonal Cycle, Pruning, and Propagation
Seasonal Growth Cycle
Tree Aeoniums are winter-growing plants, actively putting on new foliage and size from fall through late spring. This cycle adapts to their native Mediterranean climate of cool, moist winters and hot, dry summers. As summer approaches, the plant enters dormancy; the rosettes visibly close up tightly, and lower leaves may dry up to conserve moisture.
It is important to withhold almost all water during summer dormancy, as the combination of high heat and moisture causes the plant to rot quickly. The tightly closed rosettes are a protective mechanism. Normal growth resumes when temperatures cool in the autumn and the rosettes begin to open again.
Pruning
Pruning maintains the plant’s desired shape and size, and encourages a bushier growth habit. If a stem grows too tall or leggy, cutting it back (beheading) stimulates the production of multiple new side branches below the cut site. Individual rosettes are monocarpic, meaning the stem that produces a flower stalk will die after the flowers fade. When flowering occurs, the spent head should be cut back down to a branch point to allow side shoots to take over.
Propagation
The best time to propagate is during the active growing season in late winter or early spring using stem cuttings. Use a clean, sharp blade to remove a healthy rosette with a few inches of stem attached. The cutting must be left in a dry, shaded area for several days to allow the cut end to form a protective callous. Once the wound is dry and firm, plant the cutting directly into a pot filled with dry, gritty soil mix. Wait a week or two before lightly watering; roots should develop quickly in the cooler months.