I dug up one potato plant because I wanted to use some, and the potatoes looked very nice, tasted good, and were very firm but less than 2 weeks later I went to use the rest and they were very soft. I had left them outside to dry for a few days and then brought them in the house-they were stored in a dark place but not cool. Can you tell me why this happened? Is it just because it was too early to harvest them for storage? I am concerned that this will happen to the whole crop when I do dig them up. Thank you