Conventionally they are planted in spring and harvested in autumn. But when I’ve had a patch established before, I’ve just let it go and dug up a sweet potato or two whenever I want one.
I can’t say this is fast and easy. It’s a long slow Sunday afternoon recipe, and it creates quite a bit of washing up! But there’s a good return on investment – for an hour or so of Sunday afternoon baking, you can have several very healthy dinners and lunches made ready for the week.