@tennbee The idea of using plastic bottles, foam blocks, packing peanuts is primarily to make the pot lighter and use less soil. (You know how heavy a extra large pot can get when filled with soil, plants and water) Years ago I took a class at a garden center on flower arranging and a master gardener showed us how to use milk jugs and 20 oz. soda bottles and foam peanuts. Put the filler material of your choice in the bottom of the pot.Cut a piece of landscape fabric or fine screen, fit in place, add soil and plants.
My next project is to make a fountain out of a jumbo planter I have in my garage. It's a beautiful turquoise blue planter fountain kit I bought at Lowes for under $40. I can't wait to relax on my lanai to the sound of bubbling water!