I have always moved the bean and the pea bed every year. This year I want to construct a Munty type frame for beans, and I have an 'A' type frame for tall peas, both of which I'd rather not have to move every year. I asked Joe Maiden, who has a show on Radio Leeds and is a vegetable expert, if this would be a problem, at a talk he gave at a local society. He reckoned that if your plot is not troubled by disease, it would be fine. He does the same, and recommended moving the bean bed around every 6 to 7 years as the wood deteriorates. So that's what I am going to do.