In your area, I would imagine that the only place that might have them for fall would be your local feed & farm store. Last year none of ours here in Huntsville had them for the fall because most people don't grow potatoes in the fall.
When you plant them for the fall, I think you need to give yourself around 100 days before you expect the first freeze.
Last year, I used some that I kept from my spring planting. Unfortunately, I think I planted too late and didn't have a very good yield. We will see how this year goes. Spring planted crop is doing very well at this time.
