Thanks, Chris. I tend to put the tray with the lithops and the other similar succulents out in the morning and take them back at night. I even put them on my kitchen floor to avoid overnight temperatures around 5 C. However, I thought that the winter sun was not so strong to burn a pleiospilos. I would not do the same in the summer when the sun is very strong. I live in Brisbane.
Apart from exposing the plant to the morning sun only, do you think I should do anything else to save it?