Gardening-wise perlite is an acceptable substitute. It has not been associated with any asbestos risks and is comparably priced to vermiculite.
I'll let one of the experts step in to give ideas for gardening without either. As you know, the function is to keep the soil aerated and also to hold in moisture, so you might be able to just plan on stirring the soil up more each time you replant a square.
I'll let one of the experts step in to give ideas for gardening without either. As you know, the function is to keep the soil aerated and also to hold in moisture, so you might be able to just plan on stirring the soil up more each time you replant a square.