Perennial Wsidom Boost Soil Health with Leaf Mold

Leaf mold refers to decomposed leaves and can be compared to cold composting, according to Washington State University (WSU) Master Gardeners. While hot composting requires both nitrogen-rich and carbon-rich materials to make heat, cold composting ignores this mix.

The resulting product, often called “garden gold,” is a rich brown or black crumbly substance that can be terrific for your soil. WSU Master Gardeners said it’s not as nutrient-rich as compost, but may aid soil in water reten- tion, boost soil structure, and function as a soil conditioner. Leaf mold can also be a highly hospitable environment for earthworms and helpful bacteria. Since leaves, the only ingredient in leaf mold, are primarily a carbon-rich material, comparatively little heat is generated. According to WSU Master Gardeners, regular hot compost breaks down through a hot, bacteria-driven process, while leaf mold can form through a cooler and much slower process driven by fungi.

Just as you can have a compost bin, you can create a bin for these fallen leaves that allows them to transform into the soil booster known as leaf mold. Aside from the labor of gathering leaves and building a bin, many may consider the process easy. Several DIY (Do It Yourself) leaf mold bin options are available, ranging from easy to super-easy. Some require some light construction work, while others use existing materials, sometimes with slight modifications.

One method recommended by WSU Master Gardeners is to build a 6-foot x 6-foot cube-shaped bin with chicken wire or similar fencing that you fasten to four t-posts at the corners. A slightly simpler version is a cylindri- cal bin with the same kind of wire or fencing and staked into the ground. According to Master Gardeners, it should be at least 3 feet wide and deep to accommodate the volume of leaves needed for decomposition. A wood bin is also an option and can be made in similar cubic dimen- sions as above, using wooden pallets arranged in a cube and screwed together at the corners.

Leaf mold can require patience. The University of Georgia Extension recommends letting a pile sit for one to two years, since it’s a slow, cold fungal process. Leaves should stay moist but not soaking wet. Shredding can help, making decomposition faster and more uniform, with leaf mold ready in roughly one year.

Resources: Find resources for this and more at extension. wsu.edu/stevens/gardening/general-gardening-information/

The WSU Extension Master Gardener Program trains volunteers to be effective community educators in gardening and environmental stewardship. Master Gardeners provide infor- mation generated from research at WSU and other university systems. Kathy Hansen is an educator and writer living in Kettle Falls.