Dried leaves are an abundant source of organic matter that can be used for several purposes in a garden, lawn and elsewhere. The leaves can be shredded into fine pieces and used as mulch around trees or other plants. They can be added to a compost bin to complement other nitrogen-rich materials and break down into compost. In the correct proportions, the leaves can be added directly to the soil, where they will decompose slowly over time, making the soil rich. Depending on the exact type of leaves, they also can be used to make decorative arrangements or as bedding for worms along with newspaper or coir.
Prior to using any dried leaves in a lawn or garden, it is important to know from which trees the dried leaves fell. This is because the leaves from black walnut trees contain certain chemicals that can kill plants with which they come into contact as they decompose. This chemical can make entire batches of compost or mulch unusable, so black walnut leaves should be avoided entirely.
One of the most basic ways to use dried leaves is as mulch around plants or trees. The leaves can help to protect plants as they overwinter and can help to retain moisture in the soil while allowing air and water to reach the roots. Over time, the leaves will break down and help add nutrients to the soil, sometimes making them a more convenient option than bark mulches that could take much longer to decompose. To use dried leaves as mulch, they must either be a very small variety or they should be shredded with a machine or lawn mower before placement.
The dried leaves in a garden also can be used in compost bins or composted on their own in well-aerated containers, such as a box made from mesh or plastic fencing. The leaves will help to provide material that will fill out a compost pile, although they do need a source of nitrogen, such as fresh-cut green matter. Alternately, there are special compost accelerator powders that can be poured into a pile of leaves that will start the composting process given the correct amount of moisture.
Small or shredded dried leaves can be buried directly in the soil, where they will naturally break down over time. This process can take several years, depending on soil conditions and the type of leaves, but it eventually will help to rejuvenate lost nutrients in the soil. It is important to avoid adding too many leaves to the soil, however, because large quantities can actually create an optimal environment in which harmful bacteria and mold can grow.
Leaves that have dried and managed to retain their shape and some of their fall color are frequently used in fall-themed floral arrangements, wreaths and other crafts projects. Attention-getting leaves, which may be large, colorful or uniquely shaped — or all of the above — are among the most popular varieties for these uses. While one has to be certain the leaf is thoroughly cleaned beforehand, possibly organic and lacking any harmful chemicals, it is possible to paint melted chocolate onto a well-veined leaf and then to remove the hardened chocolate for use as an edible decoration on a cake or other dessert.