Autumn’s rich hues are on display all around us. Sunlit days, frosty nights, and yards covered in leaves are a trademark of the season. Soon we’ll commence raking, bagging, and disposing of leaves. What a chore. But wait, what if there was an easier way to dispose those leaves? One that would save you from bagging and benefit your garden at the same time? Let me introduce you to leaf mold — a solid gold soil amendment for your garden!
What is Leaf Mold?
When deciduous trees drop their leaves you get a free source of one of the best soil conditioners available. If you garden, you need to take advantage of this! Leaf mold is simply the result of decomposed leaves. When fully decomposed, leaves create a rich, dark brown to black humus with a crumbly texture similar to compost. Where compost adds texture and fertility to the soil, leaf mold greatly improves soil structure. It’s not the same as compost — it doesn’t have the same nutrient values — but as a soil conditioner, it’s unbeatable.
Benefits of Leaf Mold
Up to 80% of all nutrients that trees extract from the ground end up in its leaves. Plus leaves contain twice the mineral content of manure. It’s good stuff! When decomposed, leaves provide the perfect habitat and food source for your soil’s microbes and earthworms. You want your microbes and worms to be happy and healthy. Leaf mold also has high water-retention properties, making it a wonderful amendment for clay or compacted soils. Turning leaf mold in with a rich compost will restore the soils structure, water-holding capabilities, texture, and of course, fertility. It’s golden!
How to Make Leaf Mold
It couldn’t be easier to make leaf mold. In its most basic form, all you need are leaves and time. Leaves can be piled in a bin or cage or just heaped in an unused area of your yard. Depending on the size of the leaves and the size of the leaf pile, it can take anywhere from two to three years to fully decompose. In a hurry? Shred your leaves and the decomposition time reduces to about a year — or less.
Shredding leaves is fast and easy with a mower. Concentrate the leaves in a layer and run your mower over them. The finer the shred the faster the decomposition. I try not to get too fine a shred, as it becomes difficult to get all those tiny bits collected! Then place your leaves in a pile, cage, or bin.
Last year, I used a square of plastic fencing to contain the leaves. This year, I’m adding a second cage made from two panels of thin, steel re-mesh (used in concrete work).
To further enhance decomposition, your leaf pile should be kept moist (heading into winter, that won’t be an issue, but it’s a good idea next summer), and it can be turned.
Last fall, my 4 x 4 x 4 foot cage was filled with whole leaves and I never turned the pile. The resulting leaf mold was about 85% decomposed — with the bottom 1/3 completely decomposed (and crawling with big, fat earthworms who now live in my raised beds!). I tore up any whole leaves that remained before adding them to the soil.
How to Use Leaf Mold
Leaf mold can be worked into your garden soil in the fall along with compost (remember, leaf mold has a low fertility value). It can be used as mulch on top of your raised beds to prevent weeds and soil erosion, as well as mulch around perennial flowers and shrubs. Over the winter the leaf mold will breakdown, feeding the worms and microbes in your soil and improving the soil structure.
The soil in my raised beds is due for conditioning. I dug out the soil and added a layer of leaf mold. There were still some large, whole leaves, but these will continue to decompose over winter. Next I layered the soil back on and added a rich compost. Finally, I topped each bed off with a layer of straw to keep any weeds down and prevent soil erosion. By the time spring planting arrives in April, the soil will be rich and ready to go!
Leaves in The Rest of the Garden
If you don’t have the space or time to make leaf mold, you can still use freshly fallen leaves in your garden. To avoid weeds and soil erosion from rain and wind, cover your beds with a thick layer of chopped or whole leaves. Chopped leaves will decompose into the soil, but whole leaves should be removed in the spring. Whole leaves can create a barrier to water and keep soil temperatures cool, so you’ll want to remove these to allow the soil to warm in spring.
While it still may be a chore to rake leaves in the fall, at least put them to work in your garden and enjoy the conditioning benefits that leaf mold delivers to your soil!