Lawn Care And Stormwater Pollution Prevention

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You can help fight water pollution with your lawnmower and a broom. As you dust off your lawnmowers for the summer season, please remember these simple things you can do to reduce the algae and chemicals in your favorite waters.

Mow High

Set your mower at the highest possible setting, usually between 2.5” and 3”. This does two things: first, taller grass plants have healthier roots, which leads to a better, thicker turf that can withstand drought and second, the taller, thicker grass shades out weeds. For your last mowing of the year, lower the mower 0.5” to 0.75” to prevent winter problems.

Let it Lie

One popular lawn care misconception is that leaving clippings on the lawn after mowing causes thatch buildup. However, the truth is that thatch is caused at the root level, not from grass clippings. Letting grass clippings stay on the lawn will also allow you to skip one fertilizer application.

Sweep it Up

When mowing, be sure your grass clippings don’t end up in the street or driveway where they can be washed into storm drains. Those phosphorus-rich blades of grass will end up in your local lake or river, feeding the algae. Be sure to sweep up your clippings after you mow.

Mow Sharp

Sharpen your mower’s blades 2-3 times each year. Dull blades tear the grass rather than cutting it. The torn blades dry out, giving the grass jagged brown or white tips.


It piling leaves on the boulevard for leaf pickup, keep leaf piles several feet away from stormwater inlet grates. That way if it rains while waiting for the leaves to be picked up, it reduces the amount of leaves entering the stormwater system. The other option is to bag your leaves and dispose of them at the La Crosse Yard Waste site.


When working on a landscaping project, never dump or stockpile dirt or wood ships in the street.

Fertilize after Memorial Day

Many people fertilize earlier than necessary in the spring. If you wait until around the end of May or the beginning of June, your fertilizer will be more effective for your plants and less likely to runoff. The very best time to fertilize to get good root growth and a stronger lawn is in late fall, after Halloween when the air temperature is below 50 degrees. If you feel your lawn needs an additional application, the third best time to fertilize is in late August.

No matter the season, before you fertilize, perform a soil fertility test on your lawn to find out what nutrients your lawn really needs. The test results will tell you the proper amounts of phosphorus, nitrogen and potassium recommended for your lawn. Every UW-Extension County Office has bags and instructions for testing your soil. Soil testing typically costs $15 per sample for both lawns and gardens.

Resources: Wisconsin Master Gardener