Hints on cultivation of Haworthias and Gasterias

The activity of various collectors in South Africa continues as always to be significant, and some nurseries have realised that the demand for Haworthias continues to be quite strong and that they are worthwhile lines for garden centres to carry. Beautiful collections can be built up due to the diversity in shape, colour, size and surface structure of the leaves and growth-form of the plants.

In addition, their undemanding nature and adaptability to places totally unsuitable for other succulents, are special advantages. Apart from an unshaded position high up in the eaves of a greenhouse, or outside in the open all year round, everything is possible. They grow just as well on a window-sill or outside from May - October in a place sheltered from the rain. As regards soil, they are also easy. It needs only be loose and well-drained. No heavy loam or big stones. Those with enough room and who like to look at attractive beds, can plant them out with free root run, or in large flat trays. Most of us collectors, however, do not have much room and in this case pots are best. In my experience, deep pots in heavy-duty plastic are best to accommodate the thick fleshy roots.

With few exceptions, their growth period is April - November, interrupted by a 6 - 8 week summer rest from July to mid-August. In this period which is generally sunny and warm, they cease growth above ground. However something is going on underground, as in all the Lily family to which Haworthias belong. Every year they renew their roots, using material from the old roots. This is especially true of members of the Haworthia genus, or more simply the soft-leaved species. This means that prolonged periods of wetness at the roots during this time, can lead to rotting. Occasional spraying is fine during the rest period, but above all plenty of fresh air. As here in Western Europe, we never get 6 weeks of sunny weather in one go, care must be taken with watering. Otherwise, normal watering and feeding are required as in other leaf succulents. Some watering and spraying is also necessary in winter, but this depends on the over-wintering temperature, preferably around 10°C. However room temperatures are also OK as well as temperatures down to 5°C.

In general Haworthias are not troubled by pests, apart from the occasional mealy or root mealy bug, which can be dealt with in the usual way. I am not aware of any other pests such as red spider mites.

The propagation of Haworthias presents no problem. This can be achieved from offsets, seed, leaf cuttings, root cuttings (species with fleshy roots) and by cutting short the flower stems. (Cut them off at about 10 cm height when the first 1 - 2 flowers only have opened. As a rule the uppermost bract will form a new rosette which can then be removed and treated as an offset.) Cultural conditions for propagation are similar to those for other leaf succulents. Seed sowing, which can be done at any time of the year, gives best results on a north-facing windowsill. The temperature should be maintained between 15 - 20°C. It is important this temperature is not exceeded too much as this inhibits germination. Only when all have germinated, and seedlings have become acclimatised to the fresh air, can higher temperatures be tolerated for short periods; not before. Seeds older than one year generally do not germinate.