I know this is an old thread, but on the basis that it is a common problem, I will add my belated comments. The comment about PVA adhesive may well be right. I painted all mine with dilute PVA many years ago. They all survived for at least 15 and some 20 years, but the PVA gradually breaks down, consequently several of the pots cracked during last year's deep freeze. I am sure coating the pots is the answer so intend to try the Limestone protective coating. I am interested to know which industrial glue another contributor used, as I want to try to glue together those pots that had a clean break. I am sure if I glue them together, then hide the crack by painting the pot, I will extend their life. Other observations are that compacted soil can lead to cracking when the soil freezes, so pots with permanent plantings fair worse. I agree about good drainage, so removing the terracotta saucers which I always use in summer and raising the pots in winter is a good idea. I may try old polystyrene packing, as buying feet for all my pots will be expensive. I have also noticed that the style of the pots makes a difference. The ones with bulbous rims fair better. I would like to replace the pots that are beyond repair, but really good quality terracotta pots are difficult to find. I live on the Derbyshire/Nottinghamshire/Leicestershire border. I would be interested to know of any local retailers, or potters that sell good old fashioned simple designs that will be in keeping with my Grade II Listed estate worker's cottage and cottage garden.