It’s a tragedy that so many Autumn leaves are sent to landfills every year when they could be put to such good use in every person’s lawn and garden. Leaf mold is the best use of fall leaves and it’s so simple to make, even if you’ve never gardened before, you’ll ace it.
Leaf mold is nothing more than well-composted tree leaves and it’s miraculous for building soil. By well-composted I mean leaves that have been cold composting for better than a year.
Leaf mold is a powerful soil conditioner. At once it makes the soil spongier and helps it retain moisture and air, which benefits plant roots. As a surface mulch leaf mold is effective too, insulating the soil from extreme fluctuations in soil temperature, keeping the surface from compacting so water can easily enter, and helping the soil retain moisture by slowing evaporation. If that wasn’t enough, leaf mold also feeds earthworms and the beneficial bacteria in the soil, supporting the soil food web, and helping to reduce soil pests and plant infections. It also makes a fine amendment for potting soils (outdoor plants only).
A compost pile is broken down mostly by bacteria in a few months. Leaves are broken down by fungi in a year or more. The end result of both types of composting is humus, the dark, spongy material created when microorganisms break down organic matter.
Making leaf mold is incredibly simple.
The beauty of making leaf mold is that it requires so little effort. Simply rake leaves into a pile in the Fall, walk away, and use them the following Fall (or maybe the Fall after that). To keep the leaf pile nice and tidy (and to protect it from being carried away on the wind), many gardeners use a leaf bin, either homemade or purchased. You can easily make your own leaf bin by heading down to your local hardware store, picking up some heavy wire fencing material, and cutting a panel at least 3′ x 3′. Roll the wire into a cylinder or shape it into a square, fill it with leaves and you’re done. The best place to put your leaf bin is in a shady spot so the pile doesn’t dry out too quickly, as moisture helps speed decomposition. If the leaves dry out too quickly, throw a tarp over the top to keep the moisture in the pile.
Tools needed to make leaf mold:
- Lawn Rake
- Elbow grease
- Wire container
Buy a ready-to-go wire compost bin on Amazon: MTB Garden Wire Compost Bin
For the DIY approach, buy hardware cloth on Amazon Garden Zone Hardware Cloth
Leaf mold is a “cold” composting process, as leaves are primarily carbon (the “browns” of composting) and lack the high nitrogen materials of a compost pile. That means that decomposition is painfully slow. To speed the breakdown, add some bat guano or other bagged manure, urine, coffee grounds, grass clippings, soybean meal, or high nitrogen organic fertilizer. Shredding the leaves also helps – use a weed whacker, shredder, rotary mower or another implement of your choice.
How long does it take to make leaf mold?
In 1 or 2 years the leaf mold is ready. It will be deep brown to black in color, have a pleasant earthy smell, and will easily crumble in your hands. While this may seem like an incredibly long time to wait, I suggest you set up 2 or 3 wire bins. Empty one each year and fill it up again with fresh leaves. By rotating the bins this way you’ll always have fresh leaf mold. Keep in mind that when fully composted, your leaf mold will only be about 1/3rd the volume of your original pile of leaves.
To use the leaf mold, first sift it through hardware cloth to filter out any stones, sticks or other debris. Then spread it liberally on the garden as a soil amendment or mulch.
Don’t have the room for a wire bin? No problem. You can also make leaf mold by filling garbage bags with leaves, poking a few air holes in the bags, thoroughly wetting the leaves and then tie the bags at the top and let them sit for a year (but give them the occasional shake to stir the contents).
- Don’t use leaf mold alone as compost, as it’s essentially free of nutrients. You’ll also need compost made from yard waste and food scraps or organic fertilizers to aid plant fertility.
- Best leaves to use for leaf mold are Oak, Hornbeam, and Beech (they break down fastest)
- Shred these leaves before using, as they’re tough to decompose: Sycamore, Horse Chestnut, and Sweet Chestnut.
- Avoid conifer needles, Laurel, and Holly, as the waxy coatings on these leaves considerably slows their decomposition. These are more useful in the compost pile.
- Avoid leaves which collect on roadsides as they may contain petroleum products.
Dr. Lee Reich PhD has more information on how easy it is to make leaf mold