Answer: My first question would be why do you want to create a false bottom? If the pot has drainage holes in the bottom, it will work for planting. If not, and you add something to the bottom so excess water will drain, you'll eventually end up with bacteria laden stale water, which won't be a healthy situation for your plants (or your pot). Tall ceramic or terra cotta pots can hold potting soil without breaking so you should be able to fill it completely. If economics prevents you from doing so, you could partially fill the pot with water-filled plastic milk cartons (for weight to keep the pot from toppling over) or you could fill the empty spaces with plastic bags filled with styrofoam packing peanuts and then dump in your potting soil. Hope this answers all your questions!
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