Aloe arborescens
| Light | Full sun to bright light; tolerates some shade but flowers best in sun |
|---|---|
| Water | Moderate in the growing season; let the soil dry between waterings, keep drier in winter |
| Soil | Free-draining gritty mix (see Soil and potting mix) |
| Temperature | Best above freezing; hardy in USDA zones 9–11, tolerates brief light frost once established |
| Propagation | Cuttings (very easy); also offsets and seed |
| Toxicity | Mildly toxic to cats and dogs if eaten (sap and latex can cause vomiting) |
Aloe arborescens is a fast-growing, many-branched shrub aloe from southern and eastern Africa that builds up large multi-headed clumps of grey-green rosettes on woody stems. In the cooler months each mature head throws up a tall, conical spike of vivid red-orange flowers, making it one of the most reliable and spectacular winter-flowering aloes in cultivation. Its habit of forming dense, thicket-like stands gives it the common names krantz aloe — from the Afrikaans krans, a rocky cliff or ridge — and candelabra aloe, a nod to its branching, torch-like flower display.
Description
Aloe arborescens is a shrubby, branching aloe that can reach 2–3 m tall and just as wide in the ground, forming a rounded, multi-stemmed bush. Each stem is topped by a rosette of long, tapering, gently recurved leaves that are grey-green to bright green depending on light and season. The leaf margins carry small, pale teeth, and the whole plant takes on warmer, stressed tones in strong sun and drought.
The real show comes in autumn and winter, when mature heads send up unbranched, conical racemes of narrow tubular flowers. The blooms are typically a brilliant red to orange — occasionally yellow or bicoloured in selected forms — and are a magnet for sunbirds and other nectar feeders in habitat. Because a well-grown clump carries many heads, an established plant can be covered in dozens of flower spikes at once.
Distribution and habitat
The species has one of the widest natural ranges of any aloe, running down the eastern side of Africa from Malawi, Mozambique and Zimbabwe through eastern South Africa to the Cape. It is most at home on rocky outcrops, cliff faces and mountain slopes — the krantzes of its common name — but also grows in coastal scrub, grassland and open bush.
This adaptability across altitude, exposure and climate is a large part of why A. arborescens has become such a widespread and forgiving garden plant. It handles wind, coastal salt, poor rocky soils and short cold snaps far better than many of its relatives.
Cultivation
Aloe arborescens is among the easiest aloes to grow and a good choice for beginners. Give it full sun for the strongest colour and best flowering, and a free-draining, gritty mix — it dislikes sitting wet, especially in winter. Water moderately through the warm months, letting the soil dry between waterings, and ease off as temperatures drop. See Watering for general technique.
In frost-free and light-frost climates it is an excellent, low-maintenance landscape shrub, forming a fast, dense, drought-tolerant screen or specimen; it is widely used for security hedging and erosion control on slopes. In colder regions it makes a large container plant that can be moved under cover for winter. Established plants can get top-heavy and sprawling, so an occasional prune keeps the clump tidy — and every cutting you remove is a ready-made new plant. See Repotting when a potted specimen outgrows its container.
Propagation
This is one of the simplest succulents to propagate. Stem cuttings root almost effortlessly: remove a branch, let the cut end callus over for a few days to a week, then set it in a gritty, barely moist mix and it will root quickly. The plant also produces basal offsets that can be separated from the clump, and it grows readily from fresh seed, though seedlings are slower and more variable. See Propagation — cuttings, Propagation — offsets and Propagation — seed for full walkthroughs.
Cultivars
Several garden forms and hybrids are grown for flower colour, size or hardiness. Colour selections include yellow- and bicolour-flowered forms alongside the usual red-orange, and a variegated (yellow-striped leaf) form is popular with collectors. A. arborescens also crosses readily with other aloes and is a parent of many popular hybrid landscape aloes. See the Aloe genus page for an overview.
Common problems
- Rot — the main risk, caused by wet, poorly drained soil or overwatering, particularly in cold weather; stems and roots soften and blacken.
- Etiolation — too little light produces weak, stretched, floppy growth and poor flowering.
- Pests — mealybugs (white fluff in leaf axils), scale and aloe mite (which causes lumpy galls) are the usual troublemakers. See Pests and diseases.
See also
- Aloe — the genus overview
- Propagation — cuttings · Propagation — offsets · Soil and potting mix · Watering · Repotting