Leaves as Mulch
The first step in using dead leaves in the garden is to use them as mulch. Chop the leaves up and lay them in a 2-inch layer over the garden soil to help maintain moisture and warmth. The mulch layer will also keep weeds from growing, and keep disease-bearing soil from splashing onto the plants.
Leaves as Fertilizer
Leaves break down over time and turn into leaf mold. When the leaves break down, mix them into the top 2 to 3 inches of soil in the garden to fertilize the soil and add organic matter.
Leaves in Compost
Yard waste like leaves, grass clippings, straw and old foliage are also valuable in home compost piles. Fold the waste into the compost bin and allow it to break down, then use the compost in the garden as a soil amendment.