Join Date: Apr 2015
Thanked 57 Times in 57 Posts
If I go down to 3" I hear it from my oldest son. Without going into detail, he is a stone cold expert when it comes to lawns & lawn care, with over 25 yr's experience.
The only time he says to cut it as low as 3" is early in the spring when it's growing fast, after that, 3.5-4" is better.
I generally run 3.5" except for the last cut of the year when I'll cut it at 3". My son says that the last cut can be as short as you want as long as you're not "scalping" it. This is in Michigan and the reason to go short for the winter is to reduce the possibility of "snow mold" in the spring. By going shorter the lawn can dry out better in the spring.
I can't remember all of the reasons for cutting grass longer for most of the year but it has to do with longer blades of grass being able to generate "more energy" for a healthier lawn. On top of that he says that taller grass helps keep weed seeds from getting down to the soil as easy. I do remember that he mentioned that longer blades of grass support deeper roots and even had a "ratio" dealing with that. Deeper roots go along with the healthier aspect of cutting longer.
Another thing is to not let your mower blades get dull as that's a top contributor of lawn disease. You want to cut the grass, not tear / rip at it since that puts undue stress on it.
There can be a fine line between a rut & a groove....