This is the largest genus of Amaryllids in Africa. They occupy a vast range of habitats, from arid lowlands to snowy mountains, there are desert plants and those capable of withstanding cold and wet. In the UK they should all be regarded as tender, for safety's sake.
All Cyrtanthus need good drainage, especially the arid land species. The bigger species are better with the bulb planted above the compost. Contractile roots will pull the bulb down to the correct depth but the bigger species have thicker bulb tunics and like to be able to dry out rapidly after watering.
We use clay pots or bed them out, in a soil containing a LOT of silica sand, under glass. Never put them in peat-based compost (or similar), never use plastic pots. Most do not need much water. Let them dry out almost completely between watering. If in doubt then don't give any water.
The majority are deciduous, sometimes only briefly, but they will need a dry dormant period to ripen growth.
Available for ordering from Spring and Autumn lists.