Denny's Soapbox

Lawn Fertilizing

Most homeowners that fertilize their own lawn and most lawn care companies place too much emphasis on spring and summer lawn fertilization. Joe Rimelspach, plant pathologist from Ohio State University states that fall is the most important season to fertilize the lawn. When properly fed in the fall, the lawn only needs a small amount of fertilizer in the spring. Heavy fall fertilization of the lawn is the ideal time for all cool season grasses that compose most lawns in Ohio. Dr. John Street and Pamela Sherratt with the Ohio State University Department of Crop Science concur.

Turf managers state that turf fertilized in September and again in November generally shows better fall and winter color than turf that is not fertilized during this time period. In addition, signs of spring green-up have been shown to occur two to six weeks earlier if the turf had been fertilized the previous fall. Most importantly, the enhanced rate of spring greening is realized without stimulating excessive grass blade growth that can occur using four step fertilization programs or using most lawn care companies.

Many knowledgeable turf managers have utilized late season nitrogen fertilization referred to as late fall fertilization for many years. This type of fertilizer application includes a high nitrogen, quick release fertilizer applied in September and again in November. The selected fertilizer can also have small amounts of phosphorus and potassium included, although phosphorus is not necessary. The late fall application should be made when the lawn stops growing but is still nice and green, a condition that usually occurs in mid to late November when temperatures are in the 45-50˚ range.

Joe Rimelspach concurs. He states that early fall and late-fall fertilization benefits turf grass in several ways including rapid recovery of the lawn from summer drought damage. Weed and disease problems are also reduced using the fall fertilizer schedule and the grass plants produce more root mass and a deeper root system resulting in an overall healthier lawn.

Use the Right Stuff

To take advantage of all the benefits that fall fertilizing brings to your lawn, a lawn fertilizer that has at least 1 lb of actual nitrogen per 1 m sq. ft. of lawn should be applied with each application.

When selecting a lawn fertilizer, due the math. Multiply the first major number on the bag by the weight of the bag (ex: a bag of lawn food 28-0-4 in a 20 lb bag to cover 5,000 sq. ft.). Multiply the 28 which is the percent of nitrogen by the weight of the 20 lb bag. The answer is 5.6 lbs of actual nitrogen, the amount that should be used over 5m sq. ft. There are fertilizers that have a higher first number but the bag weighs less (ex. a bag of lawn food 32-0-4 in a 13 lb. bag to cover 5,000 sq. ft.). Again multiply the first major number on the bag by the weight of the bag (Ex: 32 x 13 lbs = 4.2 lbs. of actual nitrogen which is not enough for fall feeding.

This limited and timely fertilizer schedule does not bode well with 4-step lawn programs for the do-it-yourselfer which encourages 3 applications of fertilizer in the spring or lawn care companies that like to make five or more applications of fertilizer to your lawn each year. To date, most fertilizers labeled ‘winterizer’ do not have sufficient nitrogen for either fall application.

Late fall fertilization definitely is a case of less gives your lawn more. Your lawn will show it’s appreciation by looking its best ever.