There is still time to plant more cool season crops in the Mid-West. So there is no reason to quit gardening unless of course you want to.
Prepare your cold frames and frost covers just in case you need them.
This month you can direct sow argula, Chinese cabbage, collards, endive, lettuce, mache, mustard, parsley, peas, radish, sorrel, spinach and turnips.
September is certainly cooler and thus a good time to dig and divide perennial plants such as Hostas or Daylilies.
The cooler weather makes it easier for you to work in the garden meaning you can get work done you avoided all summer due to the heat.