Home Owners Tips
Lawn Fertilizer Application and Management for Homeowners
Many Maine residential areas are located near ponds, lakes, rivers and
coastal waters – or stormdrains that lead to these waters. These water
bodies can be degraded by excess nutrients such as nitrogen (N) and
phosphorous (P) found in the common fertilizers we use on our home lawns,
especially when these fertilizers are over applied or improperly applied.
Groundwater (drinking water wells) can also be contaminated from nutrients
applied to our lawns. Recent research has provided data that
should change the way we choose to fertilize our lawns:
Recommendations for Using Fertilizers on Lawns
- If your lawn looks healthy without fertilizers, do not fertilize. Most lawns over 10 years old do not need fertilizers. Leaving the clippings on the lawn supplies a steady, safe, free source of nutrition.
- If your lawn does not look healthy without
fertilizers, figure out why. Some causes might be soil compaction,
shade, pests or low nutrient levels. Visit
http://pmo.umext.maine.edu/homeowner/ for information on pests
and plant diseases. If fertilization is deemed necessary, here are
some things to consider:
- Always have your soil tested to find out which nutrients are lacking. It is very common for soils that lack adequate nitrogen to have plenty of phosphorous.
- Always fertilize with P-free fertilizer (only nitrogen), unless soil tests show that your lawn is lacking phosphorous. If only blended fertilizers are available, use the formula with the lowest level of phosphorous. Phosphorus is the middle number on a fertilizer bag (10-0-2)
- Slow-release fertilizers are preferred over soluble, fast-release fertilizers.
- Do not use products that include both fertilizers and weed killers (“weed and feed”). The application rates on the bag label are usually based on the weed killer rather than the fertilizer. If you need to treat for weeds, see http://pmo.umext.maine.edu/homeowner/ first.
- Apply one-half to one-third (or less) of the amount recommended on the fertilizer bag label. Reapply at this reduced rate only if your lawn begins to look unhealthy again.
- Do your math! On well established lawns, do not apply more than 2 lbs of nitrogen per 1000 square feet of lawn area per year. To calculate how much nitrogen is in your bag of fertilizer, follow this link: http://www.sustainability.uconn.edu/fertcalc.html
- Leave a buffer strip of at least 25 feet of unfertilized grasses or other vegetation around neighboring water bodies
- Do not apply fertilizers before spring green-up and apply no later than September 15th. The best time to fertilize in central/eastern Maine is around Labor Day weekend. Avoid fertilizing in the midsummer.
- Do not apply fertilizers when moderate to heavy rain is in forecast.
- Do not apply fertilizers on bare ground or sparse lawns, unless it is a new seeding.
- Never apply fertilizers to saturated/soggy or frozen ground.
- Mow as high as possible (leave at least 3 inches) and leave the clippings on your lawn. Your grass clippings act as a free and safe fertilizer: the clippings provide a source of slow release nitrogen and adequate phosphorous for your lawn.
- Consider seeding white clover or other low-grown legumes into the lawn to naturally provide nitrogen.
- When establishing a new lawn, choose grasses such as fescues that require less nutrients and water.
- Avoid over-watering your lawn. Do not exceed a total of 1 inch of water per week, including rainfall. A simple rain gauge or small narrow container placed in your lawn can help you determine how much water your lawn is receiving.
- When using organic fertilizers derived from composts, be sure to annually test soil for phosphorous to ensure that phosphorous levels do not become excessive.
- If you have a soil test, the results will include information on soil pH, as well as nutrient levels. Maintain soil pH levels between 6.0 and 6.5. Add lime according to your soil test result recommendations if needed.
Soil test kits are available from the Penobscot County Cooperative Extension or the Penobscot County Soil and Water Conservation District Offices.
For more information contact Laura Wilson, John Jemison or Lois Berg Stack at the University of Maine Cooperative Extension, 207-581-2953 or 1-800-870-7270 (in state.)
The information on this sheet is adapted from: Guillard, K. 2008. New England Regional Nitrogen and Phosphorus Fertilizer and Associated Management Practice Recommendations for Lawns Based on Water Quality Considerations. University of Connecticut. For a complete copy of this document, go to: www.umext.maine.edu/waterquality/fertilizers.htm
For additional information about soil testing, go to: http://anlab.umesci.maine.edu/
This
material is based in part upon work supported by the Cooperative State
Research, Education, and Extension Service, U.S. Department of
Agriculture, under agreement number 2006-51130-03956. Any opinions,
findings, conclusions, or recommendations expressed in this publication
are those of the author(s) and do not necessarily reflect the view of
the U.S. Department of Agriculture.