Q: I have some very large pots and filling them with potting soil is going to be expensive and make them really heavy. What can I do? A:
You can fill up to a third of the space with something lightweight and then cover that with landscape cloth to prevent soil from moving down. You can use an upturned plastic pot, crushed aluminum cans, non-degradeable packing peanuts, broken styrofoam, or other similar items as long as they are clean and won't decay, so no wood or paper products. Be sure the drainage hole in the pot isn't blocked. After you put in the lightweight stuff and the landscape fabric, add the soil, water it in, and let that drain before adding your plants. Potting soils tend to sink somewhat because watering reduces the air spaces in the soil. If you plant first and then water, your plant may end up lower in the pot than you want.