How to make leaf mold to use in your garden


We’re at the tail end of an annual battle to tame our backyards in northeast Ohio. As of November, many of our gardens have been cleaned up, our nesting boxes have been stashed away and most of the deciduous trees in our region have dropped their leaves. Only a couple of weekends remain that have the potential to be devoted to raking, blowing and bagging leaves.

Instead of tossing those leaves — and with them a myriad of beneficial nutrients and minerals — make leaf mold to benefit your yard and garden for years to come.

Leaf mold

Leaf mold is the product of letting leaves sit and decompose over time. It sounds a lot like traditional composting, but there are some nuances that set it apart.

The ideal ratio of carbon (brown material) to nitrogen (green material) for traditional composting is 24:1. Creating leaf mold only requires a pile of leaves — a 60:1 carbon to nitrogen ratio — and some moisture.

Traditional composting is a hot process where the pile heats up as its mixture of carbon and nitrogen components is broken down by bacteria. Making leaf mold is a cold process where decomposing fungi break down the leaf pile. Leaf mold takes much longer than traditional compost to break down enough to be ready for use. But it’s a simpler process because it uses only leaves and it requires less frequent mixing if you decide to mix it at all.

The result in both scenarios is dark organic humus. However, the applications are different. Traditional compost contains much more nitrogen and can be used to add organic matter to soil, improve soil composition, improve water retention and act as a fertilizer. Leaf mold has all the same benefits except for being able to fertilize the soil as effectively due to its lack of nitrogen.

Leaf mold uses

As a soil amendment. Leaf mold is an excellent soil amendment. It adds organic matter to soil and increases water retention and improves soil structure, resulting in better habitat for earthworms, beneficial bacteria and other soil insects and microbes.

  • Heavy clay soils. Leaf mold improves drainage and air circulation in heavy clay soils.
  • Sandy soils. Leaf mold helps sandy soils retain moisture better.

You can use leaf mold as a soil amendment by spreading it thickly on the surface of soil and lightly forking it in. Organisms living within the soil will do the rest of the work to break it down and fully incorporate it.

In the garden. Leaf mold can be used in your vegetable garden, flower garden or around trees and shrubs to increase biological activity and add organic matter and minerals to the soil. Although leaf mold does not contain a ton of nitrogen, it’s rich in the calcium and other minerals your soil needs. Leaf mold can improve crop yields, plant health and plants’ resistance to disease. Work leaf mold into the soil by spreading a thick layer and lightly forking it or tilling it in. Leave several inches of space around the trunks of trees and shrubs.

For potted plants. You can use leaf mold in place of peat moss to lighten the soil in potted plants. You can also use it to make your own potting mix with compost and weed-free topsoil

To reduce runoff. Leaf mold can hold up to 500% of its own weight in water, allowing it to absorb rainwater and reduce runoff in your yard. And in hot weather, it helps keep roots cool by retaining moisture.

As mulch. When it’s used as mulch, leaf mold can moderate soil temperature, help soil retain moisture, suppress weeds and gradually improve soil. Additionally, it doesn’t have to be completely broken down to be used as mulch, so it can be used sooner.

Leaf mold should be spread at least 1-2 inches thick, but no more than 3 inches thick to be used as mulch. Again, space around the base of trees, shrubs and plants should be maintained.

How to make leaf mold

  1. Use the right leaves. Leaf mold is made of deciduous tree leaves. Leaves high in lignin (cellulose) — magnolia, holly and some oak leaves — take longer to break down. Larger leaves like big leaf maple and sycamore can also take longer to break down. Whereas, smaller leaves like birch and alder break down faster. Leaves to avoid include black walnut, eucalyptus, camphor laurel and cherry laurel because they release chemicals that can negatively affect plant growth.  
  2. Collect leaves from your yard by raking or blowing them into a pile. Don’t collect them from busy roads or other areas where they may have come into contact with pollutants. You can also arrange them into strips to go over with your lawn mower and bagger. Chopping them up before piling them will help them break down faster.
  3. Make a pile that’s out of the way where it can sit to decompose for 1-2 years. The pile should be about 6 feet in diameter and 5 feet high to retain enough moisture to decompose.
    You can also keep your pile in a wooden or wire enclosure to help contain your leaves while allowing air to circulate around the sides. Enclosures made from pallets or wire hardware mesh work well. Make sure the pile is moist before covering and check periodically to make sure it’s moist throughout the year.
    Or you can leave your leaves in black trash bags to decompose. Just smash them down, moisten them, shake them to distribute the water and tie them shut. Then poke some holes in the bags with a garden fork. Store the bags out of direct sunlight.
  4. Periodically check your leaf pile or bag to make sure it’s moist. Water it when necessary. You can also stir the pile or add green material like in a traditional compost pile to speed up the process.
  5. Leaf mold is ready to use when it’s soft and crumbly. However, it doesn’t have to be completely broken down to be used as an effective mulch.

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