I have read this article about using styrofoam (Polystyrene) instead of Perlite. Is it good to plant Haworthias in 100% styrofoam grains?
The poly's water retention is inferior to that of Perlite, and is closer to that of pumice. The polystyrene balls are easily obtained when you rub a piece of the stuff against a rough surface and all the "grains" break loose.
Setting aside all other issues while processing this stuff, how good will be a 100% styrofoam-based substrate to plant Haworthias? Will the water retention be sufficient for Haworthias?