Mowing Matters

Living in a landscape of lawns as we do, it would seem knowing how to use a power mower would be second nature.  But as I watched someone blow clippings all over a sidewalk and hit a crabapple tree with a push mower from my office window, I discovered yet another teachable moment.

Let’s start with height.  Mowing grass that is 4 inches high down to 3 inches is just right.  This observes the “1/3 rule,” which states that removing just that much from the grass plant is best for it’s health.  It also leaves the grass tall enough to shade out weeds and maintain a generous root system, yet short enough that it looks good.  Using a mowing height shorter than 2.5 inches is asking for a weed invasion, since grasses are weakened and more light reaches the soil surface.  On some riding mowers, you just turn a dial or move a lever to set the height.  My walk-behind is more complex, but fiddling with the lever on each wheel and using a ruler makes it possible.

Clippings can cause controversy.  As a teenager I liked hitching the Parker Sweeper to my dad’s mower, since this meant that I didn’t have to spend hours raking and carting the mess to the compost pile.  But things have changed since the 70’s, even mowing.  About 30 years ago, researchers from Texas A & M University studied lawn clippings and came to a number of conclusions.  Unless they are clumpy, clippings don’t hurt the lawn, but in fact add back a tremendous amount of nutrients, and they don’t contribute to thatch.  Leaving clippings on the lawn makes less work, and also keeps them out of the landfills.  This was all big news at the time.  In fact, one of my first tasks as a new Cooperative Extension agent in 1989 was to educate folks about “grasscycling,” as we called it then.  Some folks warmed to the idea, while others kept on collecting.

The big breakthrough came when manufacturers perfected the mulching mower.  Using modified or multiple blades and new deck designs, these modern marvels chop up the clippings much finer than the mowers of yesteryear.  My dad’s old Simplicity made piles of debris, whereas my new John Deere produces very little.  I haven’t picked up clippings in years, and my lawn is all the better for it.  My neighbor still collects, bags, and hauls it all to the town dump, but only because his wife makes him do it.

Of course, challenges remain.  Mowing wet or tall grass can be problematic, and fast driving, dull blades or a clogged deck add to the misery.  But blowing grass clippings onto sidewalks and roadways or into waterways or storm drains is my biggest pet peeve.  Clippings are rich in nutrients, and end up polluting lakes and rivers.  In fact, a recent University of Minnesota study found that up to 36% of water pollution from households came from two sources:  grass clippings and pet waste.  So watch where waste goes.