How often should I fertilize my lawn?
In Iowa, Kentucky bluegrass lawns can be fertilized in spring (April or May), mid-September, and late October/early November. The number of fertilizer applications is largely determined by an individual’s desires or expectations for their lawn.
Three applications of fertilizer (the first in spring, the second in mid-September, and third in late October/early November) would be appropriate for individuals who want a vigorous, dark green lawn. A single application of fertilizer in late October/early November would be sufficient for individuals who prefer minimal fertilization. A moderate fertilization plan consists of an application of fertilizer in mid-September and second application in late October/early November.
Each application of fertilizer should consist of one pound of actual nitrogen per 1,000 square feet.