How to grow them?
Most of the plants from genus Haworthia (+ Haworthiopsis and Tulista), Astroloba and Gasteria are not difficult, you can grow them as other succulent plants. In Winter they excuse temperatures as low as 5 degrees. In Summer they welcome good ventilation. In nature you find them often growing under bushes, in grass or among rocks. This ensures them protection from direct sun and domestic animals (sheep and goats) which consume them without hesitation. Just a few species, e.g. H. leightonii, H. glauca, H. coarctata or H. reinwardtii grow in direct sunlight. From April till September I install 30% density shade cloth over my greenhouse. I have installed two larger ventilators inside greenhouse and they are running nearly 24 hrs a day. Basic rule - in South Africe the wind is always blowing!
Significant advantage in growing is that more than 75% plants can grow for a long period in a 7cm pot and it is not a problem to house quite a large collection in a small greenhouse or window parapet. The largest Haworthia specimen grows to max. 15-20 cm in diameter (e.g. T. maxima, T. kingiana or T. marginata). Genus Gasteria belongs to larger succulents (in size) – some species are in mature size almost 1m when mature (e.g. G. acinacifolia, G. croucheri and others), but we can also find smaller species like G. baylissiana, G. elaphiae, G. glauca or G. glomerata. Most of Astroloba genus can be grown on more sunny place. "Healthy color" is dark green. If you plants are too bright green (and rosette is not compact), that´s the sign they need a bit more sun. In case of reddish color (except of H. leightonii) you need to shade them a little.
|Collection of plants from cooperi group|
It depends on the soil mixture you are using and fresh air movement. I grow my plants in pure pumice (washed, 1-8 mm). I water my collection in growing season (in Spring – from March / April till July and in Autumn from September till November) once in two weeks. In winter once per month or two. During Summer, when days are too hot I stop watering. In case of cooler rainy period I give them water.
In my case, when I´m using pumice, where there is not much sustenance at all, I have to fertilize my collection regularly. I do it with every watering in a very low density 0,0005% of Wuchsal Super. A basic rule is to use fertilizer with a balanced ratio of Nitrogen-Phosphorus-Kalium.
|Large comercial nursery in Holland|
In contrast to other genera Haworthia, Astroloba and Gasteria are not so tasty for pests. Rarely you find “Mealy Bugs” (a white fluffy mass appears on plant or roots). The worst threat is, in my opinion, watering at the wrong time in combination with no fresh air circulation – water can stay in the middle of the rosette and the plant will rot immediately. The characteristic smell shows that something is going wrong.
Which substrate to choose? The main requirements are leakiness and airiness. You can use normal substrate designed for succulents. Lot of nurseries and specialized collectors use pumice. It is a kind of soil volcanic origin. I have got my whole collection in pure pumice and have great experiences with it. The only disadvantage I found is, that plants run dry very quickly and I have to water them more often – also in Winter. Most of the plants can form nice root system - that´s the sign you grow them well!