How to green this grass up (Pittsburgh PA)

The three primary plant nutrients are nitrogen, phosphorous and potassium. The NPK ratio, the three numbers on any fertilizer, represent these numbers and show the percentage of each in a sack.

Of all of them, nitrogen is the primary nutrient plants need it is taken up by plants the fastest but also bonds with the soil differently and can leach through it. Plants can only take up nutrients so fast and depending on the soil quality and health. Plants also need other minerals and also a balanced Ph range to grow properly. Only a soil test can tell you where you stand and what you should add to improve and balance your soil.

Over nitrogenation is a big problem. In the turfgrass industry we aimed for 1 pound of nitrogen, per 1,000 sf, per month of the growing season for turf. That may have been too much in some areas.

While you are correct that nitrogen will green up a lawn, you do not want to apply it at a rate higher than suggested. Nitrogen runoff changes the environments of rivers and streams and the lakes and ponds they flow into. Giant algae blooms are just one obvious sign. Over nitrogenation of Midwest farmland is leading directly to the demise of corale and shrimp populations in the Gulf of Mexico and has inspired several international lawsuits.

Anyhow, back to your lawn. I think you probably over applied. If you had 50-0-0 half the sack you bought was nitrogen. If it was a 50 pound sack, you had enough to feed 25,000sf. I am guessing you applied it to less turf than that? Common mistake. But you probably burned or perpetuated a fertilizer burn.

Now then, if the turf was already brown the other things you need to look at are the soil test results. You also need to rule out insect infestation--particulary grubs and any sort of fungus infection. The latter can really take hold if you water late in the day and the turf is left wet overnight. These can be treated with insectisides and fungicides.

As mentioned, you can address your weed problems next year too.

Now then, if your grass went brown as fall approached another possibility is that you have some sort of bermuda or similar turfgrass breed. I cannot really tell what you have from your photo but a real nursery should be able to help you. It is natural for bermuda and other similar species to turn brown in the fall and there is nothing to do about it short of dying it. All the fertilizer in the World will not keep it green. I've never heard of it surviving in your climate though. It could be a crabgrass too I guess (again a better picture showing it in relation to the soil would help) and most are annuals and will die off.