Does it make sense to plant “fall crops” if you live somewhere with an early winter, like zone 6 or colder?
I think it does, but it also makes sense to broaden your concept of what “fall crops” are.
In my garden, I plant Romain lettuce and cilantro in early and mid August, but that’s about it as far as planting stuff goes. Other than that, a good deal of the greens that I planted in the spring, like kale and Swiss chard, after producing all summer long, continue to produce well into October and sometimes November in certain years.
Then there’s also the root vegetables, like carrots, beets and parsnips. I grow a lot of these each year, but I really don’t start eating the beet and carrots until September, and the parsnips don;t even get touched until December!
Finally there’s the winter squashes, which are all left alone until Octoberish, and which keep very well in my garage for most of the winter when stored properly.
So have “fall crops” does not necessarily mean having the plant a lot of things in late August. With proper planning, most of your fall crops can be planted in the spring, and they’ll just spend all summer long getting bigger, better, and tastier until you get around to eating them in the fall!