I have 3 hypertufa pots that I made with a Portland cement, perlite and peatmoss mixture. We live in Zone 6 with below freezing winters and they have all held up just fine for several years. This one is the biggest and oldest probably a good 10 years old and has been outside year round for at least 7. This large size was framed over a cardboard box (beer box) and also has chicken wire in it as it was so large. We covered the box with a plastic trash bag, then covered it with a layer of the mixture and wrapped with chicken wire and then a second layer of mixture. The other two smaller pots don't need the extra support of wire. They are about 3 years old and have held up just as well with a couple of freezing winters under their belt as well. I will post pic of the smaller container later.
I will say that this large container is pretty heavy, not near as heavy as it would be if it was just poured concrete but still has some weight to it.
