If you've been putting off feeding your garden soil all summer or couldn't get to it because there were too many plants in the way, fall is a great time to amend your soil. Laying down a 3-4 inch layer of organic matter and working it lightly into your garden soil will get the worms and microbes working earlier and the freezing and thawing throughout the winter will help to work the organic matter down to plant roots, helping to break up clay soil in the process.