Temperatures have been falling this week, dipping down into the 40’s and now is the time to prepare your lawn for the cooler weather. September, October and early November, after grass has stopped growing, and spring are the best times to fertilize lawns in Iowa. According to horticulturists with Iowa State University Extension and Outreach, in the fall yards should be fertilized at a rate of three-quarters to one pound of nitrogen per 1,000 square feet. Also, lawns can be aerated in the fall. Aeration relieves soil compaction and improves water and nutrient movement. They advise, for best results, aerate lawns when the soil is moist with 20 to 40 holes per sqaure foot using a core aerator.