I am not someone who readily does as they’re told. Ask my mum. You know those annoying children for whom every other sentence is “Why?” Well that’s me. As an adult. I think it may explain why I am self-employed.
Anyway: so when some horticulture lecturer told me, or I read somewhere, or just received osmotically as wisdom passed down from gardener to gardener, “you must rotate your crops every year, without fail”, I did it for a while: then started to ask myself, “yes, but why?” And perhaps more importantly, “Does it really work?”

The theory behind rotating your crops is straightforward. You group your crops into families – that’s legumes, brassicas and roots (subdivided, often, into alliums – onions – plus Solanaceae (potatoes and, confusingly, tomatoes) and other roots like beetroot).
Most similar crops require the same types of care, so it’s more practical. They also suffer from the same sorts of pests and diseases: so cabbage root fly larvae, for example, can’t eat pea roots. The idea is that if you move your cabbages to a different place on the plot each year, when any overwintering cabbage root fly larvae wake up in spring they will find not cabbages to eat but peas instead – so they’ll die out. You therefore prevent the build-up of pests and diseases on the plot.
Or do you?