Question: What can I use besides styrofoam as lightweight filling in a planter?
Answer: Styrofoam packing peanuts placed in plastic bags are good fillers. Failing that you can use sheets of newspaper crunched into balls and placed in plastic bags. Be sure to seal the bags so the paper stays dry.
Q&A Library Searching Tips
When singular and plural spellings differ, as in peony and peonies, try both.