Or you could go for something completely different, like Jeruselem Artichoke, they grow tall and flat against a fence, have a lovely yellow flower, a bit like a smaller sunflower, when they die off in late autum, just cut down to about 6-8inches to mark where they are, and you can then dig up the tubers from November until March, for a lovely nutty flavoured veg, that can be used in soups, stews or simply roasted and eaten. You will never find all the tubers, so they just grow again the next year, and the next,and the next. lovely