I also save cottage cheese and large yogurt containers when I repot vegetable seedlings from the starter tray. That way they can be large and healthy when I plant them in the garden.
I also cut milk cartons in half and make pots of them. When it's time to plant, the pot easily rips and comes off the root ball. Sadly, I have let go of my community garden plot and am now inundated in milk cartons. But they are too good to throw away!
