Hi! I've been throwing away the square plastic pots for many years.  This year I noticed there was a sign at my local greenhouse, where I obtain my herbs, flowers and vegies.  I returned 2  years worth of pots (I hate throwing them out) with tray for carrying, they were tickled pink to have them back for reuse!!  Best wishes on your gardens!

 good to know, we usually have 50-70 plants transplanted from those 4pak/6pak trays. 

The ones I've gotten have been marked on the bottom as recyclable, so I tossed them in my local recycling collection bin. 

I reuse mine to start seeds each year. When they finally break (some are pretty flimsy), I put them in the recycling bin :o)

I have been washing and recycling mine for years!

Before you recycle those pots or pak/trays, which are usually black, check to see if they take black plastic. Many recyclers won't take any black plastic. My county, which has won awards for its recycling, has a notice in its recycle site that it does not acceptable pback plastic  of any kind.