I recently built a new home and am doing all of the seeding myself. The grade slopes quite drastically to the walkout basement so I planted grass there as soon as I could to avoid having it erode away during a heavy rain. The grass came up beautifully and got very tall. Being in the middle of moving and wrapping up everything related to that I didn't have time to mow it. After about 2 months went by I noticed that the grass started to slowly died off and, now has completely died. Is this due to my not mowing it that it somehow smothered itself out or is there a deeper issue here? Possibly heat?