The Easiest Way to Make Leaf Mold to Improve Your Soil

The word “mold” probably conjures up undesirable things, but when it comes to your garden and in particular, leaves, mold is exactly what you want!

I’ve been making leaf mold in my garden for years because it’s one of the easiest ways to turn organic matter into something good for the soil (microbes love it!) and it uses free materials that might otherwise go to the landfill.

(It’s shocking to me that people actually bag up leaves and leave them on the curb for garbage pickup.)

We all know that fall leaves are a great source of mulch if you don’t have straw or other materials around. And you should certainly leave some of the leaves over winter to support your local ecosystem. But sometimes you just have too much! So if that’s the case, leaf mold is a good way to recycle them back into the garden.

While the process is slower, it’s mostly hands-off (no turning required!) so the trade-off is often worth it, especially if you already have piles and piles of leaves sitting around and nowhere for them to go. (You can only put so much brown matter into that other compost heap, anyway.)

Here is the easiest way I’ve found to make leaf mold…

Smaller leaves, however, like those from aspen, willow, birch, and certain species of maple trees, naturally decay faster. This could mean finished leaf compost in six months versus two years.

If all you have are large leaves, I highly recommend sending them through a leaf shredder first.

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You don’t have to shred your leaves to make this work, but it’s helpful if you have lots of deciduous trees on your property because you can compost a larger amount of leaf litter in a smaller space. A leaf mulcher can turn 11 bags of fall leaves into just 1 bag—the hard part is raking them all up to begin with.

This is a great way to score some free leaves if you don’t have any—or enough—deciduous trees to make leaf compost. As I found out when I first started doing this several years ago, other people are quite eager to have you take unwanted leaves off their hands!

But, you can also reuse 40-pound bags that once held dog food, chicken feed, or bird seed. They’re free (my local feed store actually has a recycling bin outside where people deposit their empty bags) and they hold just the right amount of leaves.

I don’t recommend using paper yard waste bags because while they’re more sustainable, they’ll disintegrate in the time it takes to make leaf mold.

Tie or seal the bag and place it in an out-of-the-way spot in your yard. If you live in a harsh climate, store the leaf bag outside but out of the elements, so you don’t end up with rips or holes when you come back to it next year.

The goal is to exclude light and hold in moisture, which provides an optimal environment for fungi to grow. Huge populations of fungi are already present on leaves, and the carbon matter becomes their food source. As fungi multiply, they consume the leaves and speed up decomposition.

Periodically check the bag and add more water if the leaves feel too dry. The goal is to keep them slightly moist like a wrung-out sponge.

Your leaf mold is ready when the leaves have sufficiently decomposed into organic matter that no longer resembles the original leaves. The compost should be dark, crumbly, fresh and earthy smelling—never stinky and never sopping wet.

To incorporate into your soil or add to your potting mix, let the leaves sit for a while longer so they break down more and become finer. The smaller the leaves are to start with, the speedier the process.