Aeonium

How to care for Aeonium

Light

Aeonium arboreum thrives in bright light and will tolerate several hours of direct sun, particularly morning sun. A south- or west-facing windowsill is ideal indoors. Insufficient light causes the rosettes to become loose and etiolated, and the stems to lean strongly towards the light source. Unlike many succulents, aeoniums are winter growers and appreciate the brightest available light during the cooler months.

Watering

Water moderately during the active growing season in autumn through spring, allowing the top half of the compost to dry out between waterings. During summer dormancy, reduce watering significantly, giving just enough to prevent the leaves from shrivelling. Overwatering, especially in warm weather or poorly drained compost, is the most common cause of failure; always empty saucers after watering and never let the roots sit in standing water.

Soil and potting

Use a gritty, free-draining compost such as a proprietary cactus and succulent mix, or create your own by combining two parts peat-free multipurpose compost with one part horticultural grit or perlite. Good drainage is essential; heavy, moisture-retentive compost will cause root rot. Terracotta pots are preferable to plastic as they allow excess moisture to escape through the pot wall.

Feeding

Feed with a balanced, diluted liquid fertiliser at half strength once a month during the active growing period, broadly from September through to May. Avoid feeding during summer dormancy. A fertiliser formulated for cacti and succulents is suitable, as its lower nitrogen content reduces the risk of soft, weak growth.

Humidity and temperature

Aeonium arboreum tolerates the low humidity typical of centrally heated homes without difficulty. It prefers temperatures between 10 and 27 C and does not like prolonged exposure to temperatures below 5 C, though brief frost will damage it severely. In the UK it can be moved outdoors to a sheltered, sunny spot from late May to early September, but must be brought in before the first frost. Avoid placing it near radiators or heat vents, which can cause desiccation.

Repotting

Repot every two to three years in spring, or when roots visibly fill the pot or emerge from the drainage holes. Choose a new pot only one size larger, as aeoniums are somewhat tolerant of being slightly root-bound and oversized pots retain too much moisture. After repotting, wait one week before watering to allow any damaged roots to callous over.

Pruning

Pruning is not strictly necessary but can improve the plant's appearance and encourage bushier growth. Leggy stems can be cut back by one-third to one-half in early autumn. Individual rosettes can be removed and propagated. After flowering, the rosette that produced the flower spike will die; cut it away cleanly at the stem to allow side shoots to fill the space. Always use clean, sharp scissors or a knife to avoid introducing disease.

Is Aeonium toxic?

Common problems

How to propagate

Stem cuttings

Cut a healthy rosette with 5 to 8 cm of stem using a clean, sharp knife, allow the cut end to callous in a dry location for 24 to 48 hours, then insert into barely moist, gritty compost. Roots typically develop within four to six weeks at around 18 to 20 C; avoid overwatering during this period.

Offsets

Mature plants produce side shoots or offsets at the base of stems; these can be cut away from the parent plant with a sharp knife once they are a few centimetres tall and have their own rosette, then treated as stem cuttings and potted individually.

Seed

Sow fresh seed on the surface of moist, gritty compost in spring, do not cover, and maintain a temperature of around 21 C. Germination is slow and variable, and seedlings take several years to reach a presentable size; this method is rarely used by hobbyists but is of interest to collectors seeking specific cultivars.

Where Aeonium comes from

Native to Canary Islands, Madeira, Morocco, Cape Verde.

Story and origins

The genus name Aeonium is derived from the ancient Greek word 'aionios', meaning eternal or everlasting, a reference to the plant's succulent nature and apparent ability to survive drought and adverse conditions. The specific epithet 'arboreum' comes from the Latin 'arbor', meaning tree, describing the plant's characteristic tree-like, branching woody stem that distinguishes it from lower-growing rosette succulents in the same genus.

Aeonium arboreum was first formally described and named by Philip Miller in his influential work 'The Gardeners Dictionary' in 1768, though European botanists had encountered Canarian succulents considerably earlier during Spanish colonisation of the Canary Islands in the 15th and 16th centuries. The plant was introduced to European gardens as a curiosity and ornamental specimen plant, valued for its exotic, architectural appearance. It became a popular conservatory and cool greenhouse subject in Victorian Britain, and by the 20th century it had naturalised in mild parts of western Europe, Australia and California. The dark-leaved cultivar 'Zwartkop', whose name is Afrikaans for black head, became one of the most commercially successful succulent cultivars of the late 20th century, widely associated with contemporary architectural planting design.

Varieties to know

Aeonium arboreum 'Zwartkop'

One of the most popular cultivars, with deep burgundy to near-black rosettes that intensify in colour in bright light; also sold as 'Schwarzkopf'.

Aeonium arboreum 'Atropurpureum'

Similar to 'Zwartkop' but with dark reddish-purple rather than black rosettes; slightly more tolerant of lower light levels.

Aeonium arboreum var. holochrysum

A green-leaved botanical variety with bright yellow-green rosettes; less widely available than the purple cultivars.

Aeonium arboreum 'Albovariegatum'

A variegated form with creamy white and green striped leaves; slower growing than the standard species.

Fun facts

• Unlike most succulents, Aeonium arboreum grows actively during the cooler, wetter winter months and goes dormant in summer, which is the reverse of the usual houseplant pattern.
• Aeonium is monocarpic at the rosette level, meaning each individual rosette flowers once and then dies, but the rest of the plant continues to live and produce new rosettes from side shoots.
• In mild coastal areas of the British Isles such as parts of Cornwall, the Scilly Isles and the west coast of Ireland, Aeonium arboreum can be grown as a near-permanent outdoor plant, forming large, shrubby colonies.
• The flower spike of Aeonium arboreum can contain hundreds of individual small, star-shaped yellow flowers and may persist for several weeks before the rosette dies.
• The genus Aeonium contains approximately 35 species, almost all of which are endemic to the Canary Islands, with a small number found in Madeira, the Cape Verde Islands and the Atlas Mountains of Morocco.

Aeonium FAQ