Late Fall Nitrogen Fertilization For Cool Season Grasses (2023)

You've reached the Virginia Cooperative Extension Newsletter Archive. These files cover more than ten years of newsletters posted on our old website (through April/May 2009), and are provided for historical purposes only. As such, they may contain out-of-date references and broken links.

To see our latest newsletters and current information, visit our website at

Newsletter Archive index:

Late Fall Nitrogen FertilizationForCool Season Grasses (1)

Crop and Soil Environmental News, November 2003

Late Fall Nitrogen FertilizationForCool Season Grasses

Ray Smith, Forage Extension Specialist
Jonathan P. Repair, Forage Extension Agent
Scott Baker, Bedford Extension Agent
Bill Seay, Amherst Extension Agent
Late Fall Nitrogen FertilizationForCool Season Grasses (2)

Why Consider Late Fall Nitrogen Fertilization?
Most of you would agree that anytime in the fall is a good time to apply phosphorus and potassium on forage grass stands. These nutrients aid in winter stand survival, root growth and general tolerance to plant stress. Generally we do not recommend N application after mid-September because it may over stimulate lush growth when the plant should be preparing for winter. The theory behind late fall nitrogen fertilization of cool season grasses is very simple. Apply low rates of N fertilizer (40 to 50 lbs/acre) in the late fall (mid October to late November) when cool temperatures have reduced top growth, but root growth is still active. The N is used to "set-up the plant" for winter and for healthy early spring growth. Not only does enhanced root growth aid in the uptake of water and nutrients, carbohydrate buildup in the stem bases promotes winter survival and spring regrowth.

Although research results are not absolute, late fall nitrogen applications to cool season grasses have the potential to enhance stands and spring forage yields. The following advantages are suggested based on research by Dr. Dale Wolf and long standing practices with Turfgrass stands.

  1. Increasing Root Growth
    Root growth is stimulated by late fall N, but top growth is minimal during the cooler months of late fall and early winter.
  2. Increasing Plant Density
    High levels of carbohydrates in stem bases enhance the formation of crown buds and subsequent new tillers the following spring. Enhanced tillering leads to thicker stands.
  3. Increasing Drought Tolerance
    Larger, stronger root systems have the ability to maintain plants during drought periods.
  4. Decreasing Summer Weeds
    Thicker grass stands are more competitive with weeds.
  5. Cheaper Nitrogen Costs
    Historically nitrogen is cheaper in the fall vs. spring. Supply is up and demand is low dictating lower prices.
  6. Accessibility of Custom Applicators
    Custom applicator workloads are generally far below that of early spring.
  7. Applying Phosphorous and Potash at the Same Time
    Phosphorus and potassium can be applied at the same time as nitrogen with little concern for nutrient leaching.
  8. Applications Not as Weather Dependent
    Fall conditions can be drier than early spring allowing access by spreader equipment.
  9. Maintaining and/or Enhancing Yields
    Yields during the following growing season are either maintained or enhanced by late fall N applications. A recent three year two location orchardgrass study conducted by VA agents Scott Baker and Bill Seay (Bedford and Amherst counties) showed that late fall N application sometimes enhanced spring forage yields and sometimes did not, but was never a detriment.

Late Fall Nitrogen Application Timing and Rates
Nitrogen should be applied in mid to late fall once the topgrowth of cool season grasses begins to stop. This is generally mid October to late November depending on the area of the state. When applying nitrogen it is important to use a highly soluble sources (eg. Urea, ammonium nitrate, ammonium sulfate, liquid UAN). Organic forms of nitrogen (eg. animal manure) will not have the same effect on cool season grasses in late fall. Although some N in manure is in the soluble ammonium form, the majority is tied up in organic compounds and requires warm temperatures and microbial breakdown before it becomes plant available.

Once hard frosts cause the deterioration of leaf tissue, N applications are not recommended because plant uptake is minimal and applied N is wasted.

In conclusion, low rates of N (40 to 50 lb/acre) applied in the late fall to cool season grasses have been shown to improve root growth, spring regrowth, stand density, and maintain or improve forage yield. Under hay production, additional spring or early summer N applications are required for maximum production.

Late Fall Nitrogen FertilizationForCool Season Grasses (3)

VisitVirginia Cooperative Extension

Top Articles
Latest Posts
Article information

Author: Gov. Deandrea McKenzie

Last Updated: 04/07/2023

Views: 5397

Rating: 4.6 / 5 (46 voted)

Reviews: 85% of readers found this page helpful

Author information

Name: Gov. Deandrea McKenzie

Birthday: 2001-01-17

Address: Suite 769 2454 Marsha Coves, Debbieton, MS 95002

Phone: +813077629322

Job: Real-Estate Executive

Hobby: Archery, Metal detecting, Kitesurfing, Genealogy, Kitesurfing, Calligraphy, Roller skating

Introduction: My name is Gov. Deandrea McKenzie, I am a spotless, clean, glamorous, sparkling, adventurous, nice, brainy person who loves writing and wants to share my knowledge and understanding with you.