Good question and I must say that I don't know yet. These laundry baskets come in various prices and I got mine on Ebay and they were €11 each. I found that quite expensive. I then put a black bin liner into them and filled them up with potting soil and the mentioned soil amendments. I also punched a few holes into the bottom for drainage. 2 out of the 21 laundry basket containers I have bulged a bit on the bottom because I had overwatered them. Or maybe they were sitting in the sun too long without shading. Not sure, but all the other containers are ok and strong. If somebody is using heavy clay soil, I would suggest to maybe use plastic or metal drums and drill the holes in with a good drill. Together we'll find the solution for small gardens, I'm sure! Love to all!