I have a ton of pine needles I was considering using for garden mulch. Will pine needles make the soil too acidic for the plants?
Certified GKH Gardening Expert
This is a highly debated subject and pretty much depends on the soil, region, and plants. Pine needles are naturally acidic in nature. As they decompose, which is a slow process, additional acid is added to the soil. However, this may not necessarily be a dramatic increase. Since pine needles are acidic, it goes without saying that acid-loving plants (like azaleas, rhododendrons, hydrangeas, blueberries, etc.) thrive with this type of mulch. Other plants may not respond as well; therefore, pine mulch may not be suitable. So the answer to your question is basically that pine mulch does in fact affect soil pH, but is dependent on the current soil conditions.