I think using pure pumice would be ok but I would recommend removing as much of the original soil from the roots as possible with a root hook or even washing them clean. When the original root ball is in a finer mix than the new material it hold much more water and you can end up with a disaster.pone wrote: ↑Sat Aug 15, 2020 3:38 am @MikeInOz What do you think about the idea of using pure pumice for the new soil mix? It is a Euphorbia, and I will be keeping it outdoors in zone 9a, which is always a potential risk. It is already living outside in zone 9a, so no major climate change. But I would like to put the plant in a position to survive some lower temperatures.
The good thing about pure pumice would be that you could use a large pot without worrying about the unused mix going ''sour.'' Then all you need to do is throw on a handful of osmocote and you're home free...