Hilary I have seen sweet peas growing in big pots and they look lovely. I went out and counted the 'pots' that I have to keep an eye on. There are more then 100 permanent plants in clay pots, 50 plus cactus and 50 plus plastic pots with cuttings and seasonal seeds. There are more then 200 pots that I have to remember to keep an eye on and also deter the cats from sleeping among them. I am happy to add more but my sister, in her early eighties, can not cope with the work when we are away on trips.