Q: I have several large oak trees that cover my yard with leaves every fall. I try to reduce the cost of disposal by recycling them as mulch in our landscape, but they explode and cause clutter. Someone said I could turn it into leaf mold, but I don’t really know what that means. What is leaf mold and how can I use it in the yard?
A: The “leave the leaves” movement has grown over the past decade. People get the message that fallen leaves have many benefits for landscape plants and wildlife. Plus, you can save time and money by skipping raking, bagging, and leaf removal. But as you’ve noticed, leaving fallen leaves in the yard poses other challenges.
Composting oak leaves into leaf form is a great way to avoid the costs and hassles of disposing of leaves, ensuring the benefits of recycled leaves for your lawn while keeping it clean and tidy.
What is leaf mold?
Leaf mold is a dark, crumbly, sweetly earthy-smelling compost that comes from decomposing deciduous leaves. Of course, it is deposited in thin layers on the soil of the forest every year, where it supports a diverse community of microbes, insects, worms and plants living in the soil. Leaf mold greatly improves the structure of sandy or clay soils. This bulky organic matter increases the water holding capacity, aeration, drainage and nutrient buffering capacity of the soil, among many other minor benefits.
Unlike traditional compost, which decomposes rapidly during a heat-producing bacterial process, the leaves decompose slowly under cool, moist conditions, fed almost entirely by fungi. Producing leaf mold is much less labor intensive than conventional composting, but requires a little more space and can take up to a year. Leaf mold works well when applied to the surface of the soil or cultivated to the top 2 inches of the soil.
Related: 9 types of mulch to make the landscape lush
Leaf mold is an excellent soil improver when it comes to moisture retention.
Leaf mold acts as a reservoir in the soil. The porous organic matter absorbs water and creates narrow capillary gaps in the soil, improving the movement of water. The spongy texture effectively absorbs excess moisture when available and then releases it slowly when conditions are dry.
Leaf mold has been shown to increase the water holding capacity of the soil by up to 50 percent. Applying a 1-2 inch layer of leaf mold a year is like buying drought insurance. You can irrigate less often and even the driest weather will have less of an impact on your plants.
Unlike traditional compost, leaf mold does not contain many useful nutrients for plants.
Despite the structural benefits offered by leaf mold, it does not provide significant nutrient value to the soil. Although fallen leaves initially contain significant amounts of nitrogen, calcium, and many other nutrients, these valuable resources do not reach the end product. Leaf cellulose-degrading organisms use most of the nutrient content, leaving behind stable, bulky organic matter.
Leaf mold is not a substitute for fertilizer, but it creates an environment in which plants can use both conventional and organic fertilizers more efficiently and there is less potential for runoff contamination. The increased soil structure and added organic matter provide a better habitat for microbes that consume, store, and transmit nutrients to plants.
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The type, size, and condition of the leaves affect the rate of decay.
The time required to produce a dose of leaf mold can vary from 6 months to 2 years. Several factors affect the time required, including the type, size, and condition of the leaves. Type and size are related because broadleaf evergreen leaves, such as southern magnolia and holly, are thick and resistant to decay.
Decomposition is enhanced by the increased surface area. Smaller, thinner leaves offer a larger surface area per volume compared to larger, thicker leaves, so they decompose faster. Shred the leaves before processing for faster results.
The condition of the leaves also matters. If they fell in October and were collected in January, the decomposition process had already begun, shortening the time for a full batch. Moisture is extremely important to the process, so it’s best to start with wet leaves.
How to make a letter form
Leaf mold making is simple and mostly passive – and fast. Some gardeners simply apply 12 to 24-inch leaves to landscape and garden beds as mulch and allow them to decompose. But as noted above, the leaves are subject to blowing around. For better control with a little more work, leaves can be collected and a pile of leaf mold can be created. Here’s how to make a mold in a few simple steps:
- Create a cover. You can easily pile up the leaves, but a leaf compost bin will help prevent the leaves from scattering. Cut a 4-foot-long wire or nylon fence (approximately 19 feet for a 6-foot circle or 13 feet for a 4-foot circle). Fasten it in a circle and place it in a shady place.
- Collect the letters. Whole leaves decompose over time, but shredded leaves decompose faster. Use a lawnmower with a bagging accessory to shred and collect leaves at the same time, or stack them and grind them to a finer texture with a shredder.
- Fill the cover. Wrap the leaves in the cover. For the fastest decomposition, moisten the leaves when they accumulate. If the leaves fall in the area for an extended period of time, you may want to continue feeding additional leaves; the pile will shrink during decomposition.
- Moisten and cover the pile. When the trash is full or when all the leaves for the season have been collected, moisten the outer surface again. Then cover the pile with a tarpaulin to retain moisture and prevent sunlight.
- Leaf mold harvest. Check the pile in a year. Leaf mold can be used when it is dark brown, soft and crumbly. The outer layer of leaves, often dried in a pile, surrounds the inner pile of finished leaf mold. If this is the case, peel off the outer layer for further processing and clean the finished product.
Related: Composting 101 – How to Dispose of Kitchen and Yard Waste in the Garden
The best ways to use leaf mold in your home landscape
Leaf mold is an ideal mulch and soil improver for most common gardening applications. Whether we grow the plants in containers or in the ground, they serve as an excellent alternative to in-store products such as peat moss and coconut fiber. (And free.)
Because they have not been processed and sterilized, leaf mold imparts biological activity to the plant’s root zone. It contains soil-building fungi that continue to work on the soil’s coarse organic matter and attracts beneficial insects and earthworms to help with soil-forming and aeration processes. Here are some popular uses for homemade leaf mold compost.
- Insert a 2-inch layer of leaf mold into the top 2 or 3-inch portion of your garden beds for instant momentum. It can be used to improve the condition of both sandy and clay soils.
- Apply a 2-4 inch layer of black leaf cover to perennial and vegetable garden beds. Earthworms and other soil dwellers take it deep into the soil to improve noticeably over time.
- In homemade potting soil, use leaf mold as a raw material instead of peat or coconut fiber. Add equal proportions of leaf mold and perlite to obtain a loose, soil-free mixture.
- If the weed has caught up in a garden bed, use leaf mold to regain its place. Cut the weeds at ground level and let them roast in the scorching sun for a day. Cover the loaded weeds with cardboard or thick paper. Apply a 4-inch layer of leaf mold on top and wait 4 weeks before planting new plants or sowing seeds.