Most aloes are easy plants given a bright, warm location and water in moderation. Aloes require bright light, and most can take full sun in mild climates. Indoor aloes do best when placed right by an unobstructed sunny window. They prefer good drainage, especially in containers, and regular water when the soil is going dry, but not sooner. Landscape aloes are quite drought tolerant when established but will respond favorably to occasional water. Aloes from dry climates may be sensitive to excess moisture and prone to rot. + Show More
Aloes can be divided into groups based on certain features. + Show More
The “true” medicinal aloe from ancient times is Aloe vera, a yellow-flowered Arabian aloe which only exists in cultivation, and can only be grown true from offsets. This plant was formerly known as Aloe barbadensis. + Show More
The aloes which branch or offset are generally easy to start from rooted cuttings or offsets. Some can only be grown from seed. Aloe seed is usually relatively large and quick to get started. Hybrids (including many of the named hybrids in cultivation) will not generally grow true from seed, and most aloes require two flowering individuals to be pollinated (by birds, bees, or humans) and produce seed.
Open pollination in the aloe garden gives rise to all sorts of strange and interesting hybrids. Most species are quite promiscuous; a few may self-pollinate. Seed which is not produced carefully, excluding pollinators, is likely to be less than pure. Wait until the capsule dries up and breaks open to harvest mature seed (except with Lomatophyllum, which makes an indehiscent berry).
Aloe is closely related to Haworthia (white flowers) and Gasteria (pinkish flowers with a characteristic swollen shape), two mostly South African genera which generally enjoy less direct sun, as well as Astroloba, Chortolirion, and Poellnitzia (these three much less common in cultivation). Aloes may generate intergeneric hybrids with these other plants, and the hybrids may be fertile.
A recent reorganization of the aloes resulted in the splitting of a few species into the genera Kumara, Aloidendron, Aristaloe, Aloiampelos, and Gonialoe (details above), plus a few species absorbed from Chortolirion. At the same time Haworthia was split into three genera with the addition of Haworthiopsis and Tulista.
Carter, Lavranos, Newton, Walker: Aloes: The Definitive Guide (2011)
Brian Kemble's hardy aloes (list)
Castillon & Castillon: The Aloe of Madagascar (2010)
McCoy: The Aloes of Arabia (2019)