Do Oak Leaves Kill Lawns?

Acidity Consideration

• Many oak tree species thrive in acidic soils and produce leaves with high acidity, typically with a pH between 3.2 and 3.8. As the leaves lay on the lawn surface, they do not alter the soil's pH because they are not in direct contact with it. Leaves eventually decay and make their way into the soil structure, but they lose their acidity as decomposition progresses -- the leaves become more neutral or closer to a 7.0 pH value.

Proper Lawn Application

• Rake the leaves into a pile and run them through a shredder or chipper. Although brown and brittle, oak leaves do not decay quickly. Cutting them into smaller pieces makes them usable mulch for your lawn. Lightly spread the shredded leaves across the lawn so you can easily see the grass in-between. Microorganisms and earthworms, appreciate the added organic nutrients and quickly populate the area. This feeding activity aerates your lawn and releases soluble elements for grass root uptake. With proper application, shredded oak leaves decrease your lawn's thatch, or decomposing stems and foliage, because of the active microorganism feeding.

Using Your Lawnmower

• If you mow at least once a week, you can use your lawnmower as a shredding device. As you mow, allow the leaves to be cut and dispersed across the grass rather than bagging them. Do this only when the leaves are dry. Wet leaves clog the lawnmower and do not shred properly. If you have a thick layer of oak leaves, you need to rake it and shred it separately -- too many leaves mown into the turf create a thick barrier that suffocates grass blades.

Avoid Layering

• Do not allow the oak leaves to remain untouched on your lawn for long periods. As they become wet and layered, they form a barrier to rain and sunlight. The grass cannot photosynthesize and it may die back. Soil moisture does not naturally evaporate and rain cannot permeate the leaf layer. If you do not remove the leaves, your lawn may die back significantly or it could develop disease problems.