When should I fertilize the lawn in the fall?

FAQ
Question: 

When should I fertilize the lawn in the fall?

Answer: 

Fertilizer applications can be made in mid-September and late October/early November.  Mid-September fertilization promotes a moderate rate of shoot growth and helps to thicken the turf.  An application of fertilizer in late October/early November (at the time of the last mowing) promotes root growth and early green-up next spring.  Apply 1 pound of actual nitrogen per 1,000 square feet in mid-September and late October/early November.