About the genus
Haworthia is a large family of dwarf leaf succulents found in the winter-rainfall areas of southern and western South Africa. There are exceptions with H. limifolia and H. koelmaniorum growing in the summer-rainfall area in the north-east of the country and H. venosa subsp. tessellata being widespread in both rainfall regimes.
The genus Haworthia was originally erected by Duval in 1809.After recent DNA studies, the genus has undergone changes, and is now divided into the three separate genera of Haworthia, Haworthiopsis and Tulista.Previously the genus Haworthia had been divided purely on the basis of its flower shape by Bruce Bayer.
Haworthia are not normally grown for their flowers but for the amazing leaf forms, patterns and colours.They are also popular plants for producing cultivars and hybrids of stunning beauty, created by growers around the world.
Many Haworthia remain as single rosettes, with others forming clumps.They have become very popular to collect as they tend to remain small, so many plants can be grown in a relatively small space.
How to grow them
Haworthia will grow in a variety of potting media with pumice, moler clay, grit and John Innes being some popular components, but whatever the medium it must be very well-drained with plenty of air spaces in order to avoid roots rotting. It is advised that you try and find a mixture that suits your particular growing conditions.
Haworthia have a large tuberous root system once mature.Often root loss in cultivation is experienced and it is advisable to repot your plants every two to three years, cleaning and removing any dead roots from the plant.Also remove any dead leaves and old flower stems but do not pull old flower stems if they do not come away easily as you may damage and mark new leaves at the centre.
With the exception of the few summer-rainfall species mentioned overleaf, the plants grow mainly during cooler weather and stop completely in the heat of mid-summer.One also has to be very careful about any watering in mid-winter.Therefore, the plants in general respond well to being watered mainly in spring and autumn.If plants are watered too much during hot weather, they cannot absorb it, which could result in root loss.Plants kept in glasshouses will need shade from the sun as temperatures rise in summer.
The recommendation is to feed Haworthia both in the spring and again in early autumn at every other watering, using a low nitrogen fertiliser suitable for cacti and succulents.
The minimum winter temperature should be around 3–5°C.They do not respond well to high temperatures during winter as they may start to grow at the wrong time.
Haworthia are no different from all succulents regarding pests, with mealy bug and root mealy being the main culprits.Keep an eye out for small fluffy white areas between the leaves and around flower stems, which are best removed with a small brush dipped in methylated spirits.Sciarid fly grubs are also a problem and can be controlled with insecticide; alternatively thin strips of yellow sticky fly material placed among the plants is recommended.
Text and photos Alan Rollason
No part of this article may be reproduced without permission. Copyright BCSS and the Author 2019