Do Pine Needles Kill Grass?

by John Watkins
Growing grass around pine trees can be difficult.

Growing grass around pine trees can be difficult.

Evergreens, such as pine trees (Pinus spp.), can be valuable additions to your yard. They can provide year-round shade, cooling your house and yard, and can also be grown as screens or wind breaks. Growing a lush lawn around pines and other trees can be difficult, but not impossible. Using proper cultural practices to improve growing conditions for the grass will lead to a healthier lawn.

Growing Grass Around Pine Trees

Turf and trees are a classic combination, but that doesn't mean they always work well together. A healthy lawn requires plenty of sun, enough water and a steady supply of nutrients. When you grow grass and trees together, it creates an environment of constant competition with both plants competing for the same resources. Needle drop from pine trees can also produce a thick mat that forms a physical barrier, either retarding grass growth or killing it entirely.

The pH Myth

It is a common myth that grass will not grow around pine trees because the accumulated needles make the soil so acidic nothing will grow. While pine needles can have a pH ranging between 3.2 and 3.8 when they fall from the tree, they have little effect on plant growth because the roots are not growing in this material. As the needles break down, they are neutralized by the microbes that are doing the decomposing work and will have little effect on the soil pH.

Improving Growing Conditions

Growing a healthy lawn where pine needles fall can be difficult if you don't improve the growing conditions. Pruning back tree limbs will allow more light to reach the grass. Raising mowing heights under trees will improve the turf’s ability to compete with trees for water and nutrients. Avoid shallow watering and fertilize heavily with nitrogen fertilizer to increase a the grass's ability to adapt to the shade. Don't let a thick layer of pine needles build up. Rake up needles regularly to allow more sunlight, air, and water to reach the grass.

Using Pine Needles as Mulch

Because pine needles are slow to decompose, they may accumulate to a point where grass will no longer grow. For this reason, pine needles can make an excellent mulch around trees or shrubs where you don't want grass. Raking pine needles from lawn areas and using it where you want to keep the ground free of grass helps recycle the pine needles and benefits the garden.

About the Author

John Watkins is a landscape designer and contractor. He received his master’s degree in ornamental horticulture and landscape design. In his career, Watkins has served as a historic estate manager, horticulturist for a college campus and adjunct professor in horticulture. He has also written extensively for regional newspapers and magazine publications.

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