We buy this stuff from walmart I think it's called "LAWN FOOD", it's REALLY cheap and we put that down once or twice a year. I think it makes everything grow(weeds included) but like I said we just don't want mud everywhere, so as long as something's growing it's all good
. When we bought our house the whole yard was bare dirt/mud and we constantly were tracking it in the house.
I can't imagine how much you guys put into a nice lawn, it must be a lot of work/money.