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Fall Fertilization






Damaging winter turf conditions, such as snow mold, can be prevented by avoiding excessive applications of nitrogen fertilizer during the fall. Snow mold occurs most often during years when an early, deep snow cover prevents the ground from freezing. Snow mold is not a serious condition-- it usually means that the affected area takes longer to green-up in the spring.


Late Fall Fertilizer for Lawns

One of the best ways to maintain a healthy, weed-free lawn, is to provide timely fertilizer applications so the grass can compete with weeds and recover from stress. In cooler climates, like the eastern United States, the best times to fertilize are late spring (around the beginning of May), late summer-early fall (early September), and late fall (late November). Let's take a look at late fall fertilization and why you should make it a part of your lawn maintenance program.

When should late fall fertilizer be applied? Most experts agree that late fall fertilization should take place when foliar growth stops (or slows to the point that turf no longer needs to be mowed), grass is still green, and before the soil freezes. This period usually occurs around Thanksgiving. Application timing may vary from year to year depending on weather conditions.






Fertilizer applied in late fall can also enhance spring green-up without the excessive stimulation of growth that accompanies early spring fertilization. The green-up from a late fall fertilizer application will often last into mid-spring, eliminating the need for early spring feeding.


Why fertilize in late fall?

Fall is the time of year when cool-season turf grasses recover from summer stress-related conditions, such as drought, heat, and disease. The cooler temperatures and moist conditions are conducive to good turf growth and provided that plants are properly fertilized in late summer (early September), turf begins to accumulate carbohydrate reserves in stems, rhizomes, and stolons. Carbohydrate reserves help turf resist winter injury and disease and serve as a source of energy for root and shoot growth the following spring.

What are the benefits of late fall fertilizer?

Late fall fertilization helps maintain turf color into early winter without increasing the chance of winter injury and disease.

Fertilizer applied in late fall can also enhance spring green-up without the excessive stimulation of growth that accompanies early spring fertilization. The green-up from a late fall fertilizer application will often last into mid-spring, eliminating the need for early spring feeding.

When compared to early spring applications of nitrogen, late fall fertilization increased rooting in spring.

Timing is everything!

Studies show that late fall fertilization does not increase winter injury, snow mold, or annual bluegrass encroachment. However, fertilizer applications made in mid-fall (mid October to early November) while turf is actively growing, may increase potential for winter injury and disease, especially snow mold.






Although it depends on weather conditions which of course, vary from year-to-year, most turf experts agree that fall fertilization should occur when foliar growth has stopped or slowed to the point the turf does not need to be mowed, the grass is still green and before the ground freezes. This time is generally around Thanksgiving.


How much fertilizer should I use?

For Kentucky bluegrass/perennial ryegrass/ fine fescue lawns and grounds, use one-pound of soluble nitrogen per 1,000 sq. ft., or one-and-a-half to two pounds of slow release nitrogen per 1,000 sq. ft. Fertilizers containing higher percentages of quickly available nitrogen would be preferred for the late fall treatment. Controlled release sources like sulfur coated urea and IBDU are also good. Nitrogen can be applied alone, or as a part of a complete fertilizer.

Most late fall fertilization programs include moderate amounts of nitrogen, phosphorus, and potassium. Both phosphorus and potassium can benefit turf when applied in late fall, but there is no benefit to applying excessive amounts. Application rates should be based on a soil test. Phosphorus is important in root growth and maturation of turfgrasses. Potassium is used by turf in relatively large amounts. It enhances rooting, cold hardiness, disease resistance and wear tolerance.

Remember:

Late fall fertilization is one piece of a year-round lawn fertilizer program. It should take place when shoot growth ceases, the grass is still green, and before the ground freezes. Don't apply any fertilizer to frozen soils.

Benefits of fertilizing in late fall include better winter color, enhanced spring green-up, and increased rooting.

Low to moderate amounts of soluble nitrogen provide good turf color without excessive shoot growth in early spring. However, slow-release nitrogen sources can also provide a good color response in early spring when used at higher rates.

To avoid potential leaching and runoff problems, use slow release nitrogen on sandy soils.

Application Techniques






After applying fertilizer, check surrounding walkways for any granules that may have spilled. Sweep away the excess fertilizer to prevent it from entering storm drains and ultimately contaminating surrounding bodies of water.


o Use only the amount of fertilizer called for, based on turf type and a lawn's square footage.
o Use a rotary spreader, which applies fertilizer more evenly, allows for a quicker application, and helps avoid a striped fertilizer pattern in the grass.
o Spread the fertilizer in at least two directions for each application (i.e. half the amount in one direction and half in the opposing direction).
o Water the turf well immediately after fertilizing.
o Sweep up any fertilizer spilled on paved areas and save for later use.
o Use slow-release fertilizers whenever possible, since they last longer and don't have to be applied as frequently as quick-release varieties.

Adapted from "Late Fall Fertilization: A Prescription for Turf Recovery," by Dr. Pete Landschoot, Department of Agronomy, Penn State University, The Keynoter, Volume 23, No.4

References: Lamey, H. Arthur, Cynthia L. Ash, and Ward C. Stienstra. 1988. Lawn Diseases, PP-950(ND) or AG- FO-3386(MN). NDSU Extension Service, North Dakota State University. MN Extension Service, University of Minnesota.

Turf Facts

2/3 to 3/4: Pounds of actual nitrogen per 1,000 square feet per application, the ideal amount for fall fertilization of fine fescues, perennial rye and turf-type fall fescue. Source: John Deere

16: The number of chemical elements required by turf grasses for growth and development. Carbon, hydrogen, oxygen, nitrogen and phosphorus are among these elements. Source: University of Illinois Extension Outreach







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