Aloe marlothii
| Light | Full sun; bright light year-round |
|---|---|
| Water | Regular in the warm growing season, sparingly in winter; always let the soil dry out between waterings |
| Soil | Gritty, free-draining mix (see Soil and potting mix) |
| Temperature | Best above freezing; tolerates light, brief frost once established; USDA zones 9–11 |
| Propagation | Seed (primary); see Propagation — seed |
| Toxicity | Like other aloes, the yellow leaf sap contains aloin (anthraquinone glycosides); ingestion can cause vomiting and diarrhoea in dogs and cats, so keep pets from chewing the leaves |
Aloe marlothii is a large, single-stemmed tree aloe native to southern Africa, widely grown for its bold silhouette and dramatic winter flowers. It carries a dense rosette of broad, spiny grey-green leaves atop a sturdy trunk, and produces striking, horizontally angled, multi-branched racemes of orange to yellow flowers — a display that has earned it the common name mountain aloe.
Description
Aloe marlothii is one of the largest of the single-stemmed aloes, eventually reaching several metres tall. It forms an unbranched trunk topped by a broad rosette of thick, fleshy, lance-shaped leaves. The leaves are grey-green, often flushed with a bluish or reddish tint in strong sun and drought, and are armed with reddish-brown spines scattered across both the upper and lower surfaces as well as along the margins — an unusually well-defended leaf that helps distinguish the species.
Old, dried leaves typically persist against the trunk as a shaggy "petticoat" rather than dropping cleanly, a common feature of tree aloes. The flowering display is the plant's signature: tall, heavily branched inflorescences in which the flower-bearing racemes are held at a distinctive near-horizontal angle, densely packed with tubular orange to yellow-orange flowers. Flowering occurs in winter, drawing sunbirds and other nectar-feeders in habitat.
Distribution and habitat
The species is widespread across the summer-rainfall regions of southern Africa, occurring in parts of South Africa, Eswatini, Botswana, Zimbabwe and Mozambique. It is a plant of rocky hillsides, ridges and open bushveld, often growing in large stands on well-drained, sunny slopes — the mountain habitat behind its common name. In these settings it endures long dry winters, intense sun and, at higher elevations, occasional light frost.
Cultivation
Aloe marlothii is an undemanding, rewarding plant where space and climate allow, and it makes a superb architectural specimen for a hot, sunny position. Grow it in full sun in a gritty, sharply draining mix, and give it room — a mature plant becomes tall and heavy. Water regularly through the warm growing season, always allowing the soil to dry between waterings, and keep it much drier through winter to prevent rot. See Watering for general technique.
The species is more cold-tolerant than many aloes and will take brief, light frost once well established, though young plants and container specimens should be protected. In climates too cold or wet for the open ground it can be grown in a large container and moved under cover for winter; see Repotting when it outgrows its pot. As with all robust aloes, watch for scale insects and mealybugs, and see Pests and diseases for control.
Propagation
Being single-stemmed, A. marlothii does not produce offsets, so it is raised almost entirely from seed. Fresh seed sown on a warm, free-draining surface and kept lightly moist germinates readily; seedlings are slow at first but steady thereafter. See Propagation — seed for a full walkthrough. Where a branched or multi-headed plant is wanted, growers instead turn to related clumping or hybrid aloes rather than trying to force offsets from this species.
Common problems
- Rot — the usual cause of loss, from overwatering or a poorly draining mix, especially in cool weather; the base or crown softens and discolours.
- Etiolation — too little light causes weak, pale, stretched growth and loss of the compact rosette form and leaf colour.
- Pests — scale insects and mealybugs can shelter among the leaf bases; watch for white fluff or hard brown bumps. See Pests and diseases.
See also
- Aloe — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Pests and diseases