Fertilize at the right time

Wayne Wilkinson
photo – Wayne Wilkinson

By: Scott Eckert, County Extension Agent, Horticulture

Almost everyone who wants a beautiful, healthy lawn knows that they must fertilize to achieve it. But many lawn enthusiasts don´t know how to fertilize properly, and making mistakes in fertilization can lead to problems.

September is the ideal time to fertilize tall fescue (turf-type or K-31), Kentucky bluegrass and perennial ryegrass since they are all cool-season turf.  Unlike the warm-season grasses like buffalograss, Zoysia, and Bermudagrass that prefer 90 degree weather and up, the cool season grasses thrive when it is in the 60 and 75 degree range.  This is why fall is the best time for fertilizing and planting fescue.

If you are wanting a Low-maintenance lawn, you should fertilize with 1.0 pound of actual nitrogen per 1000 sq. feet. This means that if you use ammonium sulfate that is 20 percent nitrogen you would use 5 pounds of this fertilizer to achieve 1.0 pounds of actual nitrogen
per 1000 sq. feet.  A low-maintenance lawn means you are mowing less often than for a medium or high-maintenance lawn.

For a Medium-maintenance lawn, fertilize in September at the rate previously mentioned and again in November at the same 1.0 pounds of actual nitrogen per 1000 sq. feet.  You will mow a bit more but have a nice looking lawn.  It is important to water only as needed.

For a High-maintenance lawn, fertilize in September as above, in November use 1.0 – 1.5 pounds  and another 1.0 pound of actual nitrogen per 1000 sq. feet in May.  Not March or April.  Then if color or growth are not satisfactory apply 0.5 pound of actual nitrogen per 1000 sq. feet in mid-June-early – July.  High maintenance turf will require more mowing  to keep up with the fertilizer amount you are applying.  The more it grows the more irrigation it will take as well.

There is no need to exceed more than 4.0 pounds of actual nitrogen per 1000 sq feet in one season.  You can actually encourage fungal disease if your nitrogen regimen is too high.

Remember to fertilize cool season grasses at the correct time of year to get the maximum


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