It is commonly believed that evergreen needles on the ground cause overly acidic soil. Scientists say this is a myth as there are no significant changes to the soil’s pH levels. People believe this because plants have a hard time growing under evergreens. The problem is not the soil’s pH but is caused by the evergreen’s thick shade and an abundance of surface feeder roots that out-compete other plants. In our western alkaline soils pine needles make a great mulch for overwintering perennials and other plants. Unlike many mulches, conifer needles do not blow away and provide insulating airspaces. As the needles degrade, they provide needed organic matter.
Growing Home: Acidic Soil
