Leaf mold is shredded flakes of partially decomposed leaves and tree litter. It is brownish black and on its way to becoming humus, one of the building blocks of great soil.
Leaf mold can be used as a soil conditioner or as mulch in vegetable gardens and other planting beds. Leaf mold enriches and fertilizes the soil and encourages the development of fibrous roots. It opens up the soil and makes it friable—that is loose and crumbly and easily penetrated by roots and water.
Leaf mold will lighten or break up clay soil. Leaf mold also can be used as potting compost at the bottom of containers or as cover for seed.
Leaf mold will occur naturally as a stage in the natural decomposition of leaves. This can happen if leaves are left to decompose where they fall or in a compost pile. The natural decomposition of leaves can take up to two or more years.
You can speed up the process and turn autumn leaves into leaf mold for spring and summer use the following season.
How to Make Leaf Mold
- Grind or shred leaves into flakes and bits. You can use a rotary mower or a leaf shredder to shred leaves.
- Pack shredded leaves into an open-wire cylinder or bin 2 to 3 feet fall. You can use chicken wire or construction wire or wire fence.
- Add nitrogen to the leaves to speed the decomposition process. Leaves do not contain enough nitrogen to supply food for bacterias that aid decomposition; add nitrogen-rich manure, dried blood, or cottonseed meal. Add one part manure to five parts leaves or two cups of blood or cottonseed meal for each wheel barrow of leaves to speed decomposition.
- Keep the leaves slightly moist.
- Turn the leaves occasionally and let them sit for six months to a year. Leaves in a bin will not break down in one winter into a fine black leaf mold or humus—such black mold is the result of several years’ decomposition.
How to Use Leaf Mold
Add decomposing leaf mold to planting beds the following season after leaves are collected. Add leaf mold around vegetables and other plants after the soil has warmed in spring but do not fully cover plants or stems to avoid rotting.
Leaf mold will slow soil moisture evaporation during hot summers and will slow soil cooling in autumn.
Leaf mold from deciduous trees will be richer in potassium and phosphorous than nitrogen. A soil test will tell you if you need to add nitrogen to your planting beds; this can be done by simply adding well-rotted steer manure.
Planting beds conditioned with leaf mold may become slightly acid. A soil pH test may suggest the application of ground limestone to raise the soil pH. But research has shown that the addition of leaf mold will not have a long-term effect on soil acidity.
After one-season as mulch, leaf mold can be turned into the soil and will decompose into humus.