When autumn comes to a forest and the leaves drop to the ground, assorted fungi and bacteria help to transform the leaves into a rich dark humus, which feeds the trees again in years to follow. You can learn from this natural process and put it to good use in your own garden. Here are several ways you can use your leaves.

Compost your leaves
Leaves are rich in carbon, minerals and fibre. A healthy compost pile requires materials rich in both carbon and nitrogen. To maintain a healthy balance in your pile, especially in winter when most materials going into the compost pile are nitrogen-rich kitchen waste, keep a supply of leaves close to your bin in a garbage can or pail with a secure lid. Always try to add equal volumes of leaves and kitchen waste to your compost pile.

Compost surplus leaves separately
If you have too many leaves for your regular bin, use a separate compost bin for leaves only. A covered wood and wire compost bin can also be made easily at home.

To accelerate the composting process and substantially reduce the volume of leaves, shred them in a garbage can with an electric lawn trimmer, run a lawn mower over the leaves, or use a commercial chipper/shredder.

Alternate 15 centimetres (6 inches) of leaves with a shovelful of soil or finished compost, and moisten the pile. Cover the leaves with a final layer of soil.

In the spring, when the leaves have thawed, mix in a few shovelfuls of soil. During the summer, check the pile occasionally and water when dry. The leaves should turn into a rich, dark compost by the fall.

Try alternative composting methods
Place shredded leaves and handfuls of soil in garbage bags, moisten the mixture and close the bags. Once a week, shake the bags to mix the leaves and speed up their decomposition. By spring you should have leaf mold in the bags which can be dug into the garden or used as a top dressing.

Use your leaves as a mulch
Mulch is a layer of material which covers the soil surface. You can use your leaves as a mulch on your vegetable garden or flower beds. Let the worms do the mixing for you.

Fall & winter
In the fall and winter, mulch insulates your garden and prevents frost from damaging the flower beds. Apply at least 15 cm (6 in) of leaves for best results. Pile deep layers of leaves, or bags of leaves, around sensitive plants such as roses, rhododendrons and tender perennials, after the ground has frozen.

Some gardeners bag leaves on a dry day and put them on beds of root vegetables to insulate them throughout the winter. By marking the spot with a brightly painted broom handle, you can dig your carrots, rutabaga and parsnips when you want them.

Spring & summer
Save some leaves to use in the spring. As a spring and summer mulch, leaves conserve soil moisture, keep plant roots cool in the hot sun, and control erosion. Leaves will also add organic matter and nutrients to the soil.

Know your leaves
Oak, beech leaves and pine needles are more acidic than others. Add no more than 10 per cent of acidic leaves to your composter or compost these materials separately. Use finished compost on acid-loving plants like tomatoes, strawberries and rhododendrons. If you do not wish to add them to your composter, use them as mulch for acid-loving plants.

Some leaves take longer to break down than others. Oak leaves are one example. Others include such waxy leaves as laurel, rose, pine needles, holly and rhododendron. Shredding these leaves or mixing them with more nitrogen-rich materials will help to speed up the decomposition process.

Walnut and butternut leaves should be composted separately. They contain a substance which is toxic to many plants, called juglone. Shallow-rooted plants and grains, daisies, roses, Kentucky bluegrass and black raspberries are plants that are not affected by juglone. After a year of composting, the juglone breaks down and the compost can be used safely.

Adapted from materials by the Seattle Tilth Association, the Seattle Solid Waste Utility, and the Recycling Council of Ontario.