I thought I'd share that while sweet potatoes might be big enough to dig up and use now, since the 80s I've gotten the best flavor and greatest sweetness by waiting until the vines are actively dying back, often between Halloween and Thanksgiving. Maximum sweetness seems to be after a few cold snaps and the vines have died back completely. Harvested early, they can be starchy and bland vs. flavorful and sweet, which disappoints people growing them for the first time. The pic is of a harvest one autumn that was produced by just one chunk of sweet potato planted that spring.