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Fall Fertilization

"Fertilizing your lawn at the proper time this fall will answer these questions and you'll have more sustainable lawn next year" says Lin Diacont, President of the Virginia Green Industry Council.

What if I don't fertilize?

Your lawn will gradually thin and weeds may invade. Proper and timely fertilization can be good for both your lawn and the environment. There is less chance for nutrient and soil runoff to surface waters from a healthy stand of grass than bare soil or thin grass. Healthy lawns will have less disease, insect and weed problems, reducing the need for pesticide applications. Well-maintained

Timing is everything. Fall is the OPTIMAL time to aggressively fertilize cool-season turfgrasses (bluegrasses, fescues, and ryegrasses). Cooling (but still warm) temperatures and shorter days are ideal conditions to maximize root growth and food storage in cool-season turfgrasses. The period from September through November is the time of year to deliver the annual nitrogen (N) fertilization requirement, so don't miss the chance to optimize your turf quality as well as its health.

Never forget the value of soil testing. Anytime is the right time to soil test, but fall and winter months are ideal periods to modify your soil during a period when plant growth is significantly slowing. If you have not done so within the past 3 years, perform a soil test to bring your lawn up to speed in terms of pH and major nutrient levels.

Fertilizer choices. There are lots of things to consider in fertilizer selection. First, what's in the bag? Left to right, the numbers on the fertilizer bag indicate the % of nitrogen (N), phosphate (P), and potash (K) on a weight basis. Hence, a 50 lb bag of 10-10-10 contains 5 lbs each of N, phosphate, and potash (and even for liquid fertilizers, the analysis still represents % by weight). Next, look at the fertilizer label for some additional information on precisely what other nutrients are contained in the bag, and perhaps most importantly, what type of release characteristics the N has. If the source contains slow release N, you will see a reference to a certain percentage of WIN (water insoluble nitrogen) on the label. Many synthetic turf fertilizers purchased right off the garden center shelves contain between 20-30% WIN. These predominantly water soluble sources can be safely applied at levels up to 1 lb N/1000 sq ft. according to the grass and the season. Most organic manure-based fertilizers can contain up to 75-85% WIN. These materials can be applied at levels up to 1.5 lbs N/1000 sq ft and will provide very sustained growth and color responses with minimal potential for environmental impact. However, most are very low analysis (only 5-8% N by weight) and very large amounts of product are needed if trying to apply normal N-use levels. Used properly, almost any source of N can promote desirable turf responses with little if any environmental impact; it's the user, not the fertilizer, who creates the problems.

Points to Remember:

  • Turf can use fertilizer most efficiently during cooler fall months.
  • Fall fertilization increases water-holding capacity which helps in maintaining good winter color.
  • Fall fertilization is used by the lawn to build food reserves that are stored in the lawn's expanding root system.
    Proper fall fertilization prepares the turf for earlier and healthier spring green-up.
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