I have never dug up a potato sprout. My son noticed I had a few potato sprouts coming up in one of my lemon grass pots. He dug them up and potted them in a grow bag. My son had grown some potatoes in a grow bag. We thought we had harvested all the potatoes. Obviously we had missed some of the very small potatoes and they got mixed in with the dirt in the lemon grass pot.
If you take a close look at the roots, you can see little teeny white balls. Those are baby potatoes that are starting to grow on the roots.
On the second photograph you can see the very small dark potatoes that is where the sprout came from.
by Sunshine9012