I also learned too late about filling large planters with plastic bottles and cans or peanuts. I filled several planters from the bottom.
I believe I bought at least 10 large bags of Miracle grow moisture control and the planters too a bag each. I put bottles and cans in a kitchen bag ,tie it and turn it upside down, and place it in the bottom of the planter I keep at least 6 to 8 inches for potting mix.
