Sandy, I have never seen a potato plant 3 feet tall (except for Britnay's
). You must be feeding them some kind of super-food! I wonder if different varieties have different sized and shaped plants. Just found this photo of a potato plant on the interweb:
https://www.google.com/search?...
Mine were always short and bushy; I was growing them in California in zone 8. Maybe that's the difference.