Currently I try to trade or sell off as many unused trimmings or old plants as possible, whatever is left goes into my trash or minced and in the toilet with my waste water from water changes, some water goes to houseplants but most down the toilet. At least that water is treated before going back to streams. To be honest I haven't really given this issue a whole lot of thought, I'm pretty sure most of the plants that go into my trash die before they make it out of the house. The can doesn't fill up very fast so it sits for a couple days and the plants usually look pretty dry and dead before making it out to the dumpster outside. Its probably enough but if I hear otherwise I'll be sure to change my ways.
