Most historical information on fall gardening concerns beating the cold weather. In recent years the issue has been more about dealing with the heat of September and October. For the backyard gardeners, I think it is best to gamble on the cold weather than to take on the rather certain hot weather. In the inner city area we have not had a hard freeze in a number of years. When we have had cold weather the timing has been unpredictable. Last year the coldest days (no freeze) was in December. In other recent years it has been in mid to late March.
Green beans and corn are the only real tender vegetables that I raise in the fall. The corn has to be planted in August, but the beans can be postponed. Older guides say September 1 is the latest for planting. I plan to plant the Derby beans over Labor Day. Actually my daughter and grandkids will do the planting because I am still in Montana (high in mid 80s, humidity of 23%). They should be producing in mid to late October.
For most everything else I will wait until October or later. The everything else includes carrots, lettuce, turnips, greens of various sorts, fennel, broccoli and beets. In addition, I will plant parsley, chervil, cilantro and arugula. Hopefully, the parsley and cilantro will re-seed from last year. I will get chervil from Buchanan’s if it does not re-seed. Turnips and greens can be planted outside in September if the soil is kept constantly moist. These seeds germinate so fast, it is not much trouble. I like to plant broccoli and lettuce under my plant light indoors (or start in flats in the MT coolness) and transplant when the weather moderates a bit.
Spinach planting should wait until late October; sugar snap peas in late December.