When to Harvest Potatoes?

In general, when the potato plants begin to yellow, that's time.
To be sure, you could always check.
Also, I left mine in too long this year and some of them began to rot. I live in zone 8b, though, so 'hot' for me is probably not 'hot for you! Good luck.

We wait until the vines are nearly dead, then dig the tubers and spread them on a tarp to dry for overnight. Then store them in a cool, dark, dry place. If you can keep them around 40-50 degrees F they will probably store all winter. Don't let them get any cooler or they will turn sweet-tasting.

Keep checking and using as summer comes along. Dig a hill here and there, allows you to keep track.

We live in zone 5 and dig new potatoes in July, dig them up for good in August and September.