Fertilizing cool season grasses is important for healthy growth the throughout the year. What a lot of people don’t know is that the most important application of fertilizer is the one done in the late fall. Tall Fescue, Kentucky Bluegrass, Perennial Ryegrass, and the Fine Fescues are the common cool season turf grass used in home lawns. As the name implies cool season grasses grow best during the cool weather month a nigh time temperature in the fifties and a day time temperature in the upper sixties really push these grasses to flourish.
Fertilizing in the fall is best for cool season grasses. The stress from the summer heat is over and there is much less competition from weeds or damage by insects. The grass will be able to rebuild it’s self and become healthy and will be prepared again for next summer. Because of their nature it is best to feed cool season grasses two thirds of the annual fertilizer application between Labor Day and Thanksgiving. The other third should be applied in the spring. When you apply fertilizer to cool season grass in the summer months you are actually encouraging and feeding the weeds.
In cool season grasses the growth in the cool weather continues well after the top growth stops. The root system is continuing to grow and get thicker storing carbohydrates that will be used to produce the flush of new top growth you see every spring. These carbohydrates will also be used throughout the summer to supplement the grass and help it through the heat and drought of summer. A healthy root system is what will is required to produce a healthy lawn.
The only way to be sure what nutrients are lacking in your soil is to have it tested. Most cooperative extension services do this for free or a nominal fee. Fertilizer bags will give you a complete analysis of their content on the label as well as area covered and application rates. The fertilizer bag contains three large numbers N-P-K which stand for Nitrogen – Phosphorus – Potassium these are the macro nutrients. These numbers tell you the percentage of each nutrient by weight in the bag. The higher the number does not mean it is better it just means the product is more highly concentrated.
Nitrogen is required by lawns in high levels to produce good healthy growth so application rates are expressed as lbs of nitrogen per 1000 square feet. The label on the bag should give you the information you need to apply the appropriate amount. There are how ever two types of nitrogen slow release and quick release. Applying quick release nitrogen at too heavy a rate will burn the lawn. I recommend the slower release nitrogen for all the application except the first one in March than I would use a quick release nitrogen.
Remember the key to a healthy lawn all summer is to build a healthy lawn in the fall