There is nothing more fun than harvesting a crop that has been growing underground for six months. You never know what you're going to get.
Back in February & March we carefully selected seed potatoes. Due to limited space, we had to debate the virtues of each variety and decide how many of each type to grow. Terry loves Russets, I don't. I wanted to try Russian fingerlings, he was skeptical. I definitely wanted Yukon Golds, Terry wanted more Russets. I don't care for Purples, but we had some good looking Purple tubers from last year that were sprouted and ready to go. We both like Reds.
After the potatoes plants flower, you can start digging for young potatoes, carefully rooting around with your hand in the soil. I learned that I loved Russian Fingerlings. Terry did too. I don't think Terry met a potato he didn't like. Russian Fingerlings have a waxy flesh and they are narrow and knobby like fingers. Great for nuking and then grilling to finish them off.
To get a crop to store in the cellar, wait until the plants die back completely, which means that the skins have matured. Even though we've been eating potatoes for a couple months, we still had 88 lbs to squirrel away for Fall.
Note: wear gloves if you're going to use you hands to harvest your potatoes. There is nothing more painful than having the skin pull away from under most of your fingernails and then having dirt shoved way up in there.