The problem is not when to dig but where to store them after they are dug. They need to be stored in a very cool place or they will start to send up sprouts to grow again.

The potatoes are still growing if there is green on top. We wait until they are at least half brown but ours are harvested uin the fall not in the heat of summer

I prefer to let mine cure in-ground. It is the fastest and easiest method for curing. That means no digging until a week to 10 days after the tops are fully dead. Works well unless you get a torrential ground soaking rain in the process.

Dig them earlier and you will have to air cure them and risk greening and rotting. Yukons don't store well or long even under the best circumstances so you want them well cured.

Dave

I f you want them cured, leave them in the ground until the vines are completely dead. Yukon golds are not great keepers anyway so should dig as you use them until the vines are completely dead at which time you can harvest and store. They keep fairly well in a root cellar.

You can always sneak out a few for an early meal. Once they've flowered, you can expect some small spuds to be there. My first year, I had no flowers at all. When the plants started to wilt without flowering, i figured it was a total loss. I dug them up anyway, and found a pretty good harvest already. I wasn't growing enough to save, so I just pulled them all up then.

Once the tops are dying back but not fully dead tops, should you keep watering if the temps are hot and the ground is drying. Is there any growth on the potatoes if the tops have almost died back. Do you let them stay in the ground just to cure or are they actually growing.