Fertilizer Time!

It’s the first of September…that means for cool season lawns such as tall fescue, Kentucky bluegrass and perennial ryegrass, it’s time to fertilize.  After a long summer of heat, drought and pests, it’s time.

Chart courtesy of Cornell University

Why fertilize?  Medium rate applications of nutrients help the turf roots, crowns and shoots to grow, reestablish themselves and fill in voids in the turf stand.  Without adequate fertilizer, the density of the turf will be greatly reduced, aka become thin.  Under-fertilized lawns become susceptible to diseases such as stem rust as well.  The third negative outcome is that in addition to being less dense than desirable, weeds will invade or sprout from the open spaces, causing a need for extra work to control them.

The biggest effort that most homeowners fail to implement correctly is the amount of fertilizer to apply.  Most lawns in eastern Nebraska benefit greatly from a light application in late April, a medium rate of nutrients in early summer and now, another medium rate.  A medium rate is about 0.75 or 3/4ths of a pound of nitrogen per 1,000 sq. ft.  Fortunately, this is easy to calculate and apply.

Start by dividing the amount desired – 0.75 lb. by the concentration of the product, which is usually in the 20 to 30 % range.  For explanation purposes, let’s use 25%, which can easily be found on the front of the fertilizer bag, usually in the form of 3 numbers such as 25-3-5.  These stand for the % of nitrogen, phosphorous and potassium.  The last 2 ingredients are not needed in high quantities, so we calculate for nitrogen and let the other 2 come along for the ride.

The division of 0.75 by 0.25 equals 3.0 – 3 pounds of the product are needed to fertilize 1,000 sq. ft. of turf.  Pretty easy, eh?  Certainly easier than calculating your income taxes!  So, if the lawn is 1,000 sq. ft, that’s all there is to it.  If it’s bigger, say 5, 000 square feet, then you just multiply by 5; 3 times 5 equals 15, so 15 pounds of the product needs to be applied. 

It will take some adjusting with the spreader setting to apply the correct amount, but again, that’s easy, just slide the lever over a bit, estimating that if the recommendation is for the middle of the scale, then 3/4ths of a rate would be 2 or 3 clicks over to the left.

John Fech
Horticulture Extension Educator at Nebraska Extension
John Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of 2 books and over 200 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems and encouraging effective bilingual communication in the green industry. He works extensively with the media to extend the message of landscape sustainability, making over 100 television and radio appearances each year.
John Fech on EmailJohn Fech on Twitter

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.