About the genus
These beautiful little cacti are native to Bolivia and grow from the provinces of Cochabamba and La Paz in the north, down to Santa Cruz near Valle Grande and into Tarija in the south. They grow at altitudes of 1,200–4,000m.
They were little known in cultivation until the 1970s and did not really become available to collectors in the UK until ten years later. Even then they were only available through a few select nurseries until the early 1990s.
Backeberg erected the genus in 1951, but not everybody agreed with him. Cárdenas for example rejected Sulcorebutia as a genus. He described some new species as Rebutia, Aylostera or even Weingartia, which were recombined some years later into Sulcorebutia, by Ritter.
In habitat they seem to stay solitary and are often pulled down into the soil during dry spells. Their enemies are goats and agricultural encroachment as potatoes are intensively farmed in areas where they grow.
How to grow them
Like most cacti they need as much sunshine as you can give them so a greenhouse would be ideal, or even a cold frame if it is raised from the ground. Otherwise you could probably keep them on a south-facing windowsill.
Always be aware that on really sunny days they could scorch, especially in early spring, but a sheet of newspaper laid over them while the sun is really strong will be enough to stop them burning.
We like to keep both the potting mix and the water at a pH of 5, and we always use rain water which, where we live, has a pH of 6. To reduce this, add a teaspoon of white vinegar to 4.6 litres of water.
A balanced fertiliser is added to the water in early spring, then used every three weeks during the growing season. Always water early in the morning or in the early evening because if water is left on the plant, it will certainly cause them to burn.
Sulcorebutias develop a dip or groove in the centre with age, and water will collect there so it is a good idea to always have a piece of kitchen roll to hand to absorb any excess.
Always allow the plants to dry out between waterings. From the end of September through to late March do not water at all. They will survive in a greenhouse where the temperature is kept just above freezing, and we try to keep ours at 5°C.
We use a loam-based compost mixed with 2–4mm grit at a ratio of 1:1. If even more drainage is required, we use Seramis, although Perlite or pumice can also be used. Please remember that while this works for us, if you have a blend that works for you then continue to use it. Never add lime chippings as these plants grow on volcanic soil.
This is a beautiful and very floriferous genus with many species that offset freely in cultivation. The offsets are easy to root down.
Text and photos: Kathy and Keith Flanagan
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