Spring in all its wild weather swings, plant growth and flowering glory has arrived, and along with it, the chore of mowing the lawn. Many decry the labor and monotony, but evidently some do enjoy the practice, as a new video game allows one to mow a virtual yard even when rainstorms are thundering outside.
Turfgrass is presumably the most “harvested” crop on the planet, and mowing offers many benefits and unfortunately some detriments. The advantages of mowing include weed reduction (particularly if mowed at 3.5 – 4 inches), aesthetics (who doesn’t like stripes?), reduction of noxious pests such as rodents, mosquitoes and ticks (who doesn’t like less bites?), and a positive growth effect on the plant itself with higher plant density and greater uniformity. Mowing also comes with its drawbacks, including lower photosynthesis, shallower roots (especially at lower mowing heights), removal of plant nutrients such as nitrogen, and creation of wounds that lose water and can be entry points for disease-causing pathogens.
Shade also adversely affects the health of a lawn similar to mowing, by robbing the plant of energy from photosynthesis. This results in plants with thinner and longer leaves, lower shoot densities, more upright growth and shallower roots. While most attribute shade to looming trees, there is a clear connection to mowing lawns incorrectly that is often overlooked.
When our cool-season lawns are growing voraciously in the cooler temperatures of spring and fall, two aspects to mowing are critical – height and frequency. Mowing lawns to a three-inch and preferably closer to a four-inch mowing height (often the highest setting on consumer lawn mowers) greatly reduces weed incidence and results in a thicker, lusher lawn. In order to keep up with growth, mowing must also be conducted frequently, as much as two times weekly so as not to remove more than 1/3 of the leaf tissue (aka the one-third rule). Whether from time constraints or a period of constant rain, lawns are often not mowed frequently enough, and even with mulching decks clippings are left on the turf surface. These clippings, particularly in wet clumps matted down by the wheels of the lawn mower, then become trees and shade the lawn underneath. Even more problematic, these matted clumps act as a wet blanket to stifle growth and provide a warm, humid environment perfect for disease activity.
Turfgrasses evolved along with grazing animals and in nature, clippings would be collected by the stomachs of hungry beasts. Collecting clippings after mowing is not recommended since it removes free, naturally recycled plant nutrients from the lawn and disposal is problematic. Therefore, a situation of excessive clippings on the lawn surface will happen, even in the best of care. What is done when it does, can determine the density and quality of the lawn.
Two methods are suggested. Mow it again and give it a double cut. If the clippings are excessively wet and clumped, wait a while for the wind to dry out mats so the mulch deck can suck them up and disperse them. For this second cut, the mowing direction should be changed to perpendicular of the original to minimize the pressing down of clippings by mower wheels.
The second method is to employ a piece of equipment that probably should be used anyway… the blower. When mowing, clippings nearly always inadvertently end up where we don’t want them… the road, sidewalk, driveway or porch. Blowing them off pavement and back into the yard pleases the spouse and neighbors, reduces potential for them to get into and act as pollutants in our sewers and waterways, and puts nutrients back in the lawn. After doing this, simply keep on going into the yard. Find the big clumps and disperse them into the lawn canopy with bursts of wind from the blower. With matted down clippings in the ruts of mower tires, give them a little rake and/or wait for them to dry out a bit. Some satisfaction can be realized when a matted clump flies up and explodes to disappear into a bunch of individual leaf blades. Neighbors, however, may be turned from admiration to confusion as you walk the lawn and grin to the whir of the leaf blower.