I have had 16 meaties in the goat pasture all summer. They have done pretty well. 3 of them are the creepy white ones. They have been having troble avoiding getting under the goat's feet, so I moved them into a little pen this morning. I did not lock the chickens up at night, I figured the goats would protect them from anything that might consider eating them. I didn't loose any. I had to put 4 more into the tractor, because they kept escaping from the electic netting and getting into the garden. The 3 I moved into a little pen this morning will hopefully fatten up a little and we plan to butcher them in week.
I fed the chickens in the goat pasture 2 scoops of grains per day, during milking time, so they would stay out of the barn. I can't feed them too much at a time, because then the goats would get into it. I scatter the grain in the field. Between the goats and the chickens, there is not a blade of grass in the pasture and I have to provide fresh greens for all of them daily. But we have plenty of weeds, sunflowers, broomcorn, amaranth and other vegatation. It is labor we are short on. It seems only I am "capable" of picking the greens and feeding the critters

SO at least thinks of it sometimes, or helps me when he sees me doing it.
The tiny chicks we have now, are foraging outside the garlic patch. Only th big momma hens are unable to get out of it, so the babies don't stray too far. I found the babies eat teeny tiny bugs, which we have plenty of. Even though I provide them with henscratch (I run it through the blender, to make it small enough for the littlest chicks), they seem to prefer to run around and find their own goodies. Of course I also toss in plenty of other greens and stuff. The mommas have done a nice job of turning the garlic patch for us though. We just water it once in a while.
Oh yeah, we don't get any rain here in the summer and we haven't had our usual 100 plus heat wave either.
So even though you may not have much of a garden in Sept - Oct, your chickens will probably still find plenty to eat, if you put them in the garden and they will work it for you and eat the bug eggs and bugs.