I've grown out old seed potatoes just fine. They do have a set length of time before they are fully mature and the greens start dying back. Some potatoes take more or less time depending on the variety. But if you plant the ones that are sprouted now they should still have time to make at least baby taters before the cold kills the greens off. You might not get as much as a full seasons grow, but you should get some.

The grocery store ones from the fridge... might pass on those. They need time to chit if they haven't already. And if they are russets, those are longer season taters and they might not get to bigger and better eating development with good keeping skins if you plant them now.

If the seed potatoes are not all shriveled or rotted, they should have energy to grow once in the ground and watered. They grow pretty easy, go ahead and plant them.

Now do you have enough time before freezing weather to grow much to eat? They won't grow as fast as May and June. Go ahead and try, hope for a warm sunny October. You may not get much.

I agree, put those potatoes in the ground and let them grow. I seldom chit my potatoes, unless they are very large, in which case I cut pieces that have at least two eyes and throw those in the ground. I do that while planting, not ahead of time and it works for me. That's how Grandpa taught me to do it, so it's worked for us for at least 100 years.

I would also pass on the refrigerated potatoes, unless you just have some empty ground you want to experiment with. Not knowing the variety means not knowing the days required to mature, as beesneeds pointed out

I seldom buy seed potatoes unless I want a specific variety that I do not have. This year I planted Yukon Gold, Pontiac, Dakota Dawn, Kennebec, Upnorth Abundance creamer potatoes and various fingerling varieties. All were from last year's unused potato harvest and all are growing and producing just like always. I don't find that they flower more quickly or act in any way different than any other potato I've planted.

The Red Pontiac had some pretty impressive sprouts and I just cut them off, down to a couple of inches, just so they didn't stick out of the ground when I planted them. I planted them on May 14 and have been digging and using them (as well as the Yukons and Kennebecs) for a couple of weeks now. A neighbor and I have a friendly garden competition every year and although she got a ripe tomato before I did this year, my Pontiacs are outyielding hers which she grew from seed potatoes purchased at the local farm co-op. I'm actually attributing that to the composted cow manure my cattle endlessly supply me with, but I'm not telling her, LOL.

Annie