Green Up Your Lawn: Not the Lake

by Betsy Washington

Finally! Spring is really here and with it comes the annual rite of greening up the American lawn. And with the greening of the lawn, comes the inevitable "peculiar green sheen" around the edges of our lake. This green sheen is NOT the type of green we are aiming for! It is caused by excess fertilizer, particularly phosphorus, running into the lake from improper lawn fertilization.

Improper and excessive fertilization is a major source of phosphorous and nitrogen run off into our lake and ultimately the Chesapeake Bay. Phosphorus binds tightly to soil particles and soil and bank erosion is a major cause of phosphorus pollution in our streams. Excess nitrogen and phosphorus runoff causes algal blooms that reduce water clarity and decrease dissolved oxygen levels when the algae decomposes. Decreased levels of oxygen can stress and even kill aquatic life. Algal blooms tend to coincide with the most common times of lawn fertilization in spring and early fall. In fact, improper or excessive fertilization of lawns is one of the main sources of nutrient runoff pollution, which is the most severe problem facing the Chesapeake Watershed. The Virginia Department of Conservation and Recreation states very aptly that, "The health of Virginia's waterways begins in your backyard"!,

So what can you do to make sure your lawn care does not harm our lake and health? Follow these basic guidelines to green up your lawn, and not our lake.

1) TEST YOUR SOIL. Lawns do not automatically need fertilizing, so it is important to get a soil test to tell you if you need to fertilize or lime your soil. Every responsible lawn service should begin with this simple step, and should be willing to share the results of the test with you. Surprisingly, most supposedly "organic" lawn services that I interviewed do not perform soil tests, even though this is a cardinal rule in organic lawn care! Test kits can be obtained at Green Spring Park and at local libraries for a small fee and taking a soil sample is very easy.  The test results will give you specific recommendations for your lawns and save you money and guesswork.

2) USE COMPOST TO FERTILIZE. Feed your soil to feed your lawn. Healthy soils are full of soil microorganisms that partner with plants to break down and release nutrients efficiently and create rich, humus-rich soil. A healthy soil reduces or even eliminates the need for external fertilizer. Compost and organic mulches enhance the soil web and break down slowly, so that the soil microorganisms can release nutrients just when plants need them, eliminating the threat of excess nutrient runoff. Compost improves soil tilth by lightening heavy clay soils and bulking up light, loose soils. Get in the habit of applying 1/2 to 1" of compost to your lawn each year.

3) MOW HIGH. Set your lawn mower at 3" and keep your blades sharp. Taller grass crowds out weeds, and encourages deep roots, resulting in a healthier lawn that needs less water. Mow often and never remove more than 1/3 of the grass blade at one time. Reseed any bare areas for full coverage to prevent weeds and erosion and nutrient runoff.

4) LEAVE LAWN CLIPPINGS on the lawn. Consider using an electric, mulching mower. You will reduce noise and air pollution drastically. Mulching mowers will chop the grass clippings into tiny pieces that create little or no mess and readily break down into compost. You can reduce your lawn’s need for fertilizer by more than 30%, just by allowing grass clippings to decompose in place! 

5) WATER PROPERLY. Grass lawns naturally go dormant during the hot summer weeks, and will green up again naturally when rains return. If you must water, water deeply and infrequently to promote vigorous root growth that helps your lawn resist drought. This is much better for your trees and shrubs too.

6) Applications of iron can sometimes help “green” up a lawn without the use of nitrogen fertilizers.

7) FERTILIZE AT THE RIGHT TIME and only when the lawn is actively growing and able to take up nutrients. Fertilize fescue and bluegrass lawns two to three times in fall, between September and early November. Lawns do not need more than 1 lb of nitrogen per 1,000 sq. ft in a single application, and no more than 3 lbs of nitrogen/year. If you miss the fall applications, you can apply .5 lbs/1000 sq ft in early May. Zoysia and bermuda grass lawns that are brown and dormant in winter should be fertilized in summer. Be sure to remove all fertilizer from walkways and driveways before it can wash off into storm drains and our lake. In the case of fertilizer – LESS is better!

8) NEVER FERTILIZE WHEN THE GROUND IS FROZEN OR GRASS IS DORMANT. Many lawn companies interviewed give "a little boost" of fertilizer and weedkillers or pesticides for good measure in late winter/early spring and during summer when the lawn is dormant. Preemergent herbicide treatments are routinely combined with an application of fast release nitrogen and most of this will runoff straight into the lake. This is a harmful waste of money and harmful to our lake.

9) AVOID FERTILIZERS WITH PHOSPHORUS. Phosphorus has become "persona nongrata" in landscaping, especially near streams and lakes because of its harmful effects. Now there is NO excuse for anyone in Lake Barcroft to add to phosphorus runoff into the lake. If you choose to use fertililizer, use WID's No-PHOS, slow release Nitrogen fertilizer. They even deliver free to your doorstep! Make sure that your lawn service follows this advice!

10) USE A FERTILIZER WITH SLOW RELEASE NITROGEN (N) that is released gradually over time, instead of all at once.  Slow release nitrogen is listed as WIN or water insoluble nitrogen.  You want a fertilizer with a high percentage of WIN. Many "organic" lawn services I spoke with use a chicken manure based fertilizer, which contains high amounts of nitrogen and phosphorus that can cause problems for our lake. Do you remember those "dead zones" in the bay near eastern shore poultry farms and their piles of manure?

11) TREAT LAWN PROBLEMS SAFELY by hand pulling weeds or spot treating pests or weeds. Natural products like corn gluten or vinegar can help eliminate weeds without toxic side effects. You can even use a torch to spot burn troublesome weeds. Many of the "organic" lawn services that I talked to regularly broadcast pre-emergent weedkillers over the entire lawn in early spring and again in fall. When I asked why they do this, I was told that customers pay for 6 or 8 visits a year, and expect to see the companies "treating" their lawns each visit. Tell your lawn service to spot treat problems only when necessary or not at all, and to fertilize only at the recommended times with No Phos, slow release nitrogen fertilizer.

12) And my personal favorite - REDUCE (or eliminate) YOUR LAWN and the attending maintenance and pollution woes. Add a natural buffer of native plants around your property, especially to low areas that drain into the lake. Please keep in mind, that all storm runoff in Lake Barcroft runs into the lake. We do not have storm sewers that carry the runoff elsewhere. Be sure to check out some of our gorgeous, low maintenance native plants showcased in the RPA demonstration garden and in the upcoming community garden. These vegetated buffer zones prevent erosion and pollution by acting as natural sponges and filters.

For detailed information on interpreting fertilizer labels, recommended types of grass, and for more bay-friendly landscaping tips, check out: “Tips For Keeping Your Lawn Green And The Chesapeake Clean” at:, "In Your Backyard: Bay-friendly Landscaping" at

And for an amazing and easy organic lawn care tutorial see: