Delosperma (sometimes called Ice Plants) are one of the best plants for a temperate climate where the Summers can be warm and dry, and especially where the winters are somewhat mild.
Some species are REALLY hardy and can survive as well as a Sedum or Sempervivum in a Rockery of an Alpine Trough.
The hardiest species are generally regarded as being Delosperma nubigenum, Delosperma cooperi, and Delosperma floribundum.
Other species, however, are not so hardy and are better in an Alpine House, or protected from the worst winter wet by overhead covering (such as a pane of glass). Such species include Delosperma ashtonii, Delosperma sutherlandii, and the Delosperma dyeri hybrids.
A new ‘Jewels of Desert’ range was introduced by breeder Koichiro Nishikawa in the early 2000’s, and these were derived from Delosperma luckhoffii hybrids which were carefully selected for color and performance.
These are pretty frost-hardy, but only if they are bone dry in winter. They can generally stand some cold, but are not as hardy as the hardy ‘big three’ mentioned above.
Generally it is the winter wet that kills them – but very severe cold will also do it.
If you are lucky enough to live in a relatively frost-free area, or in a City where the climate is milder, these plants are really useful.
These succulent plants originate from South Africa, where they thrive in various environments including some areas that receive winter rainfall and frost.
Most of the ‘garden types’ come from mountainous areas where they get the cold dry winters and warm, wetter summers.
As mentioned earlier, some of the hardiest species are Delosperma nubigenum, and Delosperma cooperi. Delosperma congestum and Delosperma karooicum are also pretty hardy, but will not take much below -5C.
For the best chance of success, make sure these are well-drained, that they have loads of water when they are growing (but WELL DRAINED!), and that they stay pretty frost free in Winter, but COLD.
They will not do well if there is no cold in the winter, so don’t try to keep them indoors – they won’t like it.