About the genus
The genus Gasteria was erected by Duval in 1809 to encompass plants from the genus Aloe which had ‘curved’ flowers. Many Gasteria have stomach-like (gasteriform) flowers, hence the derivation of the name of the genus [gaster = stomach or belly in ancient Greek].
Gasteria are endemic to South Africa except for two species which stray into Namibia and Swaziland, and mostly grow within 50–100km of the sea, either near the coast, on cliffs, or in river valleys. Where possible they seek protection from the sun by sheltering under shrubs, in tall grasses or on shady cliffs. Most grow in the southern summer but some are winter growers.
The genus comprises about 26 species and together with additional subspecies and varieties the total number of taxa is just under 40. There are also many cultivars and variegated plants which are keenly sought by some enthusiasts for their beauty and elegance.
As juveniles, all Gasteria are distichous (with leaves arranged alternately in two opposite vertical rows). When they become adults, some remain distichous whilst others develop leaves with a triangular cross-section and spiral to become rosettes.
How to grow them
There has been a surge in the popularity of Gasteria in recent years, partly due to the availability of the choicer recently-described species, but mainly due to their ease of cultivation and the fact that they can be grown almost anywhere. They are very happy in a shady environment so can be grown on windowsills or equally under the bench in the greenhouse. A normal cactus mix soil is fine, as long as the mix is well-draining.
The plants can all be treated as summer growers in the UK watering from mid-March to late-September. The addition of a liquid feed perhaps three times during the growing season can be beneficial too.
No watering is needed in the resting period (October–March) if the plants are kept in a frost-free greenhouse. If grown indoors, though, in warmer conditions an occasional light watering is sensible.
Most Gasteria when sufficiently mature will flower during the growing season, some very early in the year and others later. In fact, if you have a large collection of Gasteria, there may be a plant in flower almost every day of the year!
Regular repotting is recommended, every year for small plants and every two to three years for larger plants. This is a good opportunity to inspect the roots and look out for any miscreant root mealy bugs. While doing this, any offsets can be removed if desired and potted up as separate new plants which is the easiest way to propagate them.
Gasteria can be raised from seed, which is a slow process, and you need to be aware of potential hybridisation unless the seed has been obtained under carefully controlled conditions.
The best way to propagate new plants is from leaves. A turgid leaf may be removed, allowed to callus over and then rested on damp compost. In a few weeks (or months) the leaf will root down and in time small plantlets will grow from the base of the leaf, which can be separated when sufficiently large.
Text and photos: Tony Roberts
No part of this article may be reproduced without permission. Copyright BCSS and the Author 2019