The Final Word: How to Mow Your Lawn Correctly
There is a great deal of misinformation circulating out there regarding the seemingly simple task of cutting your lawn. Not to worry. I am here to set the record straight on the do's and the don'ts. To quote Kaa of Jungle Book fame, “trusssst in me.”
Minimize Lawn Stress
First, you need to realize that mowing is very stressful for the grass. There are not many plants that could stand getting their tops chopped off every week. To minimize this stress, never cut off more than one third of the leaf. If your mower is set to cut at three inches, don't let the lawn get 6" high before you mow (for the math challenged among us, that would be half. Half is no bueno).
In addition, you should try to avoid cutting the grass when it is already stressed out due to heat or drought. Mowing when it's 90+ degrees might be good prep for your IRONMAN competition, but it is not so good for the lawn.
How High To Mow Your Lawn
Probably the most frequently asked question about mowing is how high. It varies with the type of grass and the time of year but the short answer is pretty darn high. For the cool season grasses (the vast majority of lawns in NOVA) during the heat of summer you want to mow at 3-3 1/2". When the grass is maintained at that height, it lowers its ET rate (evapotranspiration) which translates into not having to water as often.
The rule of thumb is to make the first cutting of the year the lowest (don't scalp it!). Then raise the blade through spring as temps increase until you reach the 3-3 1/2" setting when summer hits. Do the reverse come fall (lower the blade as temperatures fall) until you make your last cut back at the lower setting you started the year with.
The reason for that low cut to begin and end the year is tip burn. Tip burn is a result of the grass (or any plant) losing water during sunny winter days and freezing at night. If you cut close going into winter, tip burn is decreased. Then a short mow to start spring removes any tips that still managed to burn which, in turn, helps stimulate growth.
What About The Grass Clippings?
Finally there are the clippings. To bag or not to bag? As long as you mow frequently enough so clumps of clippings aren't left on the lawn, mulching your clippings is fine. They do not add appreciatively to thatch build up. In addition, the cut grass has some small fertility value. For this reason grass clippings should always be collected off of impervious surfaces (street, drive, walks) so they do not add to the pollution problem (nutrient enrichment) facing our surface waters. The exception to the mulch your clippings rule is if there is an active fungus in the lawn. When that occurs, you'll want to mow the infected area last and bag the clippings to reduce it's spread.
That’s the final word we offer on mowing the lawn...for now!
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For more lawn mowing information, check out this article by DIY Network.