How to Make and Use Leaf Mold

Compost bins
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Fall Leaves. They’re free. You’re going to rake them up anyway. Why not turn your leaves into something your garden will love you for?

What is Leaf Mold?

Simply put, leaf mold is fully decomposed leaves. Don’t turn up your nose. Leaf mold has a rich, earthy scent and a dark, crumbly texture that could make regular compost jealous.

How Do You Make Leaf Compost?

It couldn’t be easier. Just rake your leaves into a pile and let them rot. The more compact the pile, the faster they will decompose.

The leaf mold making process is very similar to making traditional compost - but easier. There is no layering involved and no turning necessary. You can simply pile your leaves and leave them to rot or you can contain them in a wire bin or any other composting contraption. Moisten them and toss a tarp or some other cover over the pile, to maintain the moisture level, if you want to speed things along.

It is very easy to create leaf mold in a bag. Those tall paper leaf bags work especially well because they allow air and water in as the paper decomposed. By spring, not only will the leaf have disintegrated, but the bag will probably have rotted too.

However, you could also use plastic garbage bags, as long as you cut or tear openings in the bag for venting. You will also need to check the contents periodically to make sure they are not drying out.

How Long Does Leaf Mold Take?

Since leaves are considered a “brown” composting material and are predominantly carbon, they can take longer to decompose than an active compost pile. An unstructured pile can take up to two years but in a bag or a 3 ft. x 3 ft. bin, you should see results within 6 - 10 months, depending on the weather and the types of leaves.

If you’re impatient, you can shred the leaves before composting them. This will greatly speed the process. If you don’t have a shredder, just run the mower over them. You should ideally turn or toss the pile every month, to ensure the leaves are decomposing evenly throughout. However, if you chose to skip this step it will not slow things down to any great degree.

Using Leaf Mold in the Garden

Leaf mold is considered a soil conditioner, a specific type of organic matter. Although it doesn’t add much in the way of nutrients, leaf mold improves the soil’s structure, texture, and water-holding ability. It also creates ideal conditions for establishing a soil ecosystem of beneficial organisms. Think of a forest floor and how rich the soil is under the fallen leaves.

Consider leaf mold a free and renewable alternative to peat, with even better water retention. Leaf mold can hold several hundred times its own weight in water and soils amended with leaf mold improved their water holding ability by almost 50%. Working 3 inches of leaf mold into the top 6 inches of soil can improve the water holding capacity of sandy soil 2 ½ times.1

In addition to improved water retention, leaf mold also helps to loosen heavy soils. Garden soils amended with leaf mold actually approach that elusive “well-drained, moist soil” that is so often recommended.

You can work leaf mold into your soil, the same way you would compost. Just add a layer of 2 - 4 inches of leaf mold and either turn it into the top 6 inches of soil or simply let it sit and wait for the earthworms to do the work for you. You can also side dress with leaf mold, ringing the periphery of plants with a couple of inches the stuff. Just be careful not to pile it up against the plant stems. Any mulch too close to stems provides shelter to chewing insects and animals and can cause the stem to rot.

The above findings are from a study done at the Connecticut Agriculture Experiment Station. They go on to say that adding a 1-inch layer of leaf mulch on top of your garden bed each year could eliminate the need for fertilizer, although their ideal recommendation is leaf mold plus inorganic fertilizer at half rate.

One last tip, don’t be shy about asking your neighbors for their unwanted leaves. If they’re going to rake them to the curb for pick-up, chances are good they will be happy to have you come by and rake them up first.      

1Research Resources: