Sometime during September to early November is the best time of year to fertilize Colorado’s bluegrass lawns, (earlier if in the mountains).
CSU recommends at least one pound of nitrogen per 1,000 square feet. The benefits of fall fertilizing include a healthier turf before winter, a healthier root system, and stimulating a turf that greens up earlier in the spring without excessive top growth. Fall fertilization produces dense, green spring lawns without the mowing chores that come with spring fertilization. It should be a part of every good lawn care program.
– September application: no later than September 3rd.
– October application: no later than September 30th.