Soft potatoes: why?

[janbee]

This morning I dug about 7 pounds of Bintje potatoes. Most were fine, but about 10 percent were soft and slightly wrinkled. The soft ones looked normal inside, so I boiled them, and they tasted as good as you would expect.

My question is: What did I do wrong? This is the first time I’ve grown potatoes, and I know that I have a lot to learn. I live in arid easternmost California (USDA Zone 8a) where summers are hot and generally rainless. This summer was unusual, because we had two substantial thunderstorms in late July and one or two lighter storms in August. Gardening here requires irrigation; I use inline drip emitters. I planted Yukon Gold and Bintje seed potatoes toward the end of April, which turned out to be about a month late for our area. I dug all the Yukon Gold potatoes over the summer as new potatoes. They were fine, if somewhat lumpy, and I was thrilled to have them. After the foliage of the Bintje potatoes started to die down, I turned off the irrigation. That was on September 4. After that, some leafy green shoots appeared in the potato bed. At least some of the soft potatoes were associated with the green shoots.

Friends who live nearby leave their potatoes in the ground all winter, but I’m wondering if I would be wise to do that, since soft potatoes are likely to rot. Does anyone have any idea why some of my potatoes were soft? And should I dig all the potatoes now? I have no place to store them except a refrigerator that is often pretty full of other stuff.

Jan