Originally Posted by Smallaxe
N is not going to be utilized in the plant for a while, as the grasses are going to grow roots off of stored carbs for a while, first... so once the soil warms up and the grasses are growing actively above ground(after 2nd mowing) then would be a good time to apply your nitrogen...
This is categorically untrue. If the plant is photosynthesizing it is utilizing nitrogen. Further, it is preferable to apply ammonium based fertilizers before
soil temperatures get above 50 degrees.