I have a 20 x 20 area of my yard that did not accept the new grass planting of last fall. The rest of the yard looks great. The bad area has been under a partial canopy of my neighbor's pine tree and I am forced to pick up large amounts of needles on a regular basis. Could the years of needles cause too much acid for the new grass? Grass seeded was fescue.
Grass Won’t Grow Well in Yard
Certified GKH Gardening Expert
I would have the soil tested. Pine trees can make the soil acidic. You will need to fix the soil or grow a grass seed that tolerates the conditions under this tree. Here is more information: https://www.gardeningknowhow.com/ornamental/trees/tgen/tips-for-growing-grass-under-a-tree.htm