You can dig them anytime after they reach a usable size. For most varieties of sweet potatoes, that's approximately 110 days after planting, but some of the early varieties reach a nice size more quickly than that. If you don't dig them earlier, they'll grow until frost,but it is better to dig them before your soil temps drop below 50 degrees in autumn.

I haven't planted them the last couple of years because my former sweet potato growing area with looser, sandier soil is now too shady, and I need to find a new spot (not easy since I mostly have clay) but when I grew them I liked to dig them in October. Sometimes in busy autumns I wouldn't get around to it until November. Since you're further north, September might work better for you. It just depends on how warm or cool and how wet or dry the weather is in the coming weeks.

It is better to dig them when the soil is dry (but not so dry it is hard to dig), and then to cure them for a couple of weeks before putting them into their storage spot. Well-cured sweet potatoes will store for several months and some years I've had them last a year in cool, dry storage.

If, by chance, today's rain signals the beginning of autumn rainfall, watch carefully for your chance to dig them when the soil is somewhere in between being too wet and too dry. Sometimes when too much rain falls after they're sizing up, it can make them crack. They are still edible, but sometimes sweet potatoes will cracked areas won't cure as well or store for quite as long.

Shelly, I have only grown sweet potatoes a few times. For me it seems best to dig around the end of Sept. or early Oct. The reason I say that is that gives me plenty time to cure them. I have left them in the ground longer, but I dont have a good place to cure them when it starts getting cold. This past year I dug mine about the end of Sept., let them lay in the sun until the soil dried very well, brushed them off with a paint brush and them stored them in a well vented part of the shed until we started having very cool nights. I then brought them into the house stored them under the bed and in the closets. The ones that kept the best were the ones stored next to an outside wall in an unheated closet. I had sweet potatoes til about a month ago. I really dont have a way to keep them cool enough for summer storage. I would like to try a closet on the north side of the house, except, I dont have one.

Larry

I have been digging mine just before the first frost and two years ago the day after a light frost. Here they do better for me if I start them later in the season it seems and then leave them in the ground as long as possible. In my deep sand I don't have the moisture issues that many do. Even 3 years ago when we finally got rain and have over 3 inches in the 2 weeks prior to me digging them I didn't have any issues. I have a few that split. I remove mine and if the weather is warm enough let them lay on the mulch for a day or so. Then move them into the expanded metal shelves in the utility room that are part of my light stand. I leave them there till I start using the shelves. I finally move the remaining ones to a cool spot in the corner. I heat the utility room but not as warm as the house. The expanded metal provides good air flow. On warm days in the autumn I leave the windows open for air circulation. It has worked well for me. I had some that stored into June this year. I finally buried one in moist soil mix to get some slips to plant. It was firm and eatable till I put it in the mix. Jay

I wait until first frost to harvest mine, but if you have extra plants, you can dig one early and leave the rest. The sweet potatoes just get bigger the longer you wait. They are fine to eat at any time, even if they're only the size of a fat finger.

Also, the leaves are edible and a good substitute for other greens. Cook them like you would collards or mustard greens. They are quite tasty, as greens go. Younger leaves are more tender and quicker cooking. Saute with a little onion, garlic and soy sauce. After they have wilted, add a little water and simmer for a few minutes if they are still chewy.

Harvest a meal off 2-3 plants without hitting any one too hard. You can do that repeatedly throughout the summer. However, if you take too many leaves, it will impact your harvest.

If the leaves are like mine you wont even have to add bacon bits, just leave the grasshoppers on them.

I tried to find some sweet potatoes today, no luck, I hope they produce. I had some once before that had very few good potatoes under them.

Larry