I got another interesting question recently. We handle tree care as well as lawn care, and you’d be surprised how much overlap there is.
“Spruce needles (lots of reddish brown needles) have fallen from very old trees onto my lawn, the trees cannot be saved, but what do I do with the lawn? Can I leave the needles or do I have to remove them?”
Evergreens drop some needles annually as part of their growing process, especially when they are old or sick. This is a problem for turfgrass because when the needles break down, they make the soil very acidic.
Once the pH of the soil starts going down, it is very difficult for the grass to absorb nutrients. That’s the main reason why you never see really healthy grass underneath pines and spruces.
You can improve the situation with regular limings – that will help bring the pH back up. Still, you will never get the grass under your evergreens to look as nice as the rest of your lawn.
Another fix would be to find a more suitable landscape idea for underneath trees, and just mulch under the base and the outer perimeter of your trees. That way you could have thick, lush grass up to the dripline of the trees with a clean transition to attractive wood mulch. Much nicer than your lawn just petering out in sickly-looking tufts.
