Here are my potato plants from bags.
These have been growing since about June 10th. The bags have been filled since June 22nd so they've just been growing since then. I've dug around for a few new potatoes but haven't found anything. I haven't tried to look very deep though.
These have been growing since June 20th. Three of them were filled to full height by July 7th, the last one was filled finally about July 15th. I haven't looked for potatoes from those little doors in the sides of the bags.
In case you wanted a reference for how big they get.
