The essentials for growing lawn grass are no different that for growing any other green plant: water, soil, mineral nutrients, and light. Basic botany, right? So when people are missing one (or more) of these essentials, no amount of the other two will compensate, and the grass won't grow. This lesson has been lost on person not too distant from TPP's neighborhood. As you can see here, some sparse newly sprouted grass is populating the shade under this tree, but in spite of adequate water (note the sprinklers and rain gauge) and presumably enough nutrients, the grass in this location is not going to grow into a thick, lush lawn; it will remain very sparse until some shade-loving weeds invade (Hello, creeping charlie!). Have you identified the species of tree yet! Well, you should have because it's one of the worst in this area for grass growing. It's a sugar maple, and they are handsome trees; some even have purple foliage. But sugar maples can make both sun leaves, bigger, thicker leaves on the outside of their crown, and shade leaves, somewhat smaller, thinner leaves adapted to the shady inner crown. As a result of this efficient light harvesting the mature crown of a sugar maple can intercept over 90% of the sunlight (figures of up to 96% have been cited) that falls upon the tree. Step under the crown and look up; what percent of the sky in view do you see? Bottom line: your grass won't grow because it is lacking an essential, light. You have no idea how often this turns up, and still sugar maples are touted as a good lawn tree. If you like your sugar maples, and you didn't prune the limbs up high enough to let in some light from the sides, you might as well give up and plant ferns or woodland wildflowers, and even some of them can't deal with shade this dense. Sorry, for the bad news; get over it. And get over the idea that lawns are just grass. If you'd asked 30 years ago, maybe you would have made another choice.