I have about 500 4" square pots that I use in my greenhouse. I used to try to get them all washed before re-using them. "Used" to. I got tired and lazy 2 or 3 years ago. So far, I haven't had a single problem using them as is. Of course, they have been empty and dry for about 6 months by the time they get used again. And I always use fresh potting soil in the greenhouse.
