what is your average first frost date? count backwards from that. also consider day length is decreasing. I am in zone 5 with first frost date about 10-15 of October. the only crop that can't take much cold weather I plant in late July is green beans. but I am not in zone 7

Our frost date here appears to be at October 30th. So we've got 2-3 more weeks. Hmm. Warm month seedlings possible?

Yep. Sounds like that's what we'll plan on doing. Turnips, Lettuce, Beans, Broccoli, etc.

I grow corn in double rows, and there is a lot of available N left in the row middles. I cut off the stalks at about a foot and plant fall kale and spinach between the rows and they do great. If I need to cover them with row cover in Sept when the deer go crazy, the cornstalks help hold it up.

some crops are much better fall crops than others. Peas have trouble germinating in warm soil. But turnip, daikon, broccoli, bok choi, cabbage, all do better as fall crops. Even after first frost, they grow during the indian summer. You can consider bush beans as well, there is time.

I would consider zucchini, but pumpkins, watermelon, and canteloupe need a long season. You would probably have luck getting some tomatoes if you wanted to try. I agree you could also do beans.

Ditto what Peter said. I set out a second crop of tomatoes this week. Any later is getting late...these were plants. Peas come up for me, but half the time the fall crop fizzles down. Broccoli, lettuce, and such do very well in the late season. Some things like lettuce will not germinate out there in July. I start butterhead lettuce indoors...74 degrees.

That sounds like a mostly good plan. Now, for peas in Idaho, you're never going to get soil so warm that they would have trouble germinating, though. Also, beans are chancy. You'll probably get something out of them, but I suspect you won't be getting full production when the first frost comes.

remember the days are getting shorter. this is a big factor with fall crops. days to harvest will be longer

I built a tool that looks at daily temps and soil temps during planting till harvest and spits out what plants will work, based on zip code. Currently does not let you specify a date in the future, but assumes today as the start date. You can check it out at http://www.edenpatch.com/weather

GrowVeg software will let you key in your own start and finish dates and take extensive notes. It's based on USDA frost date data.