We use Montmorillonite clay for extra drainage or as top dressing in our arid plants. Monto clay can be used as an acidifier when mixed with your other soil amendments. 

2 quart bag can roughly fill one and a half 6" diameter nursery pots.

1 quart bag can roughly fill one and a half 4" diameter nursery pots.

All soil amendments ship in a biodegradable bag