Mow it High and Let it Lie
Mowing is the most common cultural practice used on lawns around the world. In fact
the ability to tolerate mowing is one of the criteria that separate turfgrasses from the rest
of the grass species. There are many misconceptions about mowing that can lead to a
less than perfect lawn and many homeowners are making lawn care difficult by using the
wrong mowing practices.
Mowing Basics
Mowing is always a stress on the grass plants. Just because grass plants can tolerate
mowing doesn’t mean they like it. You can reduce this stress by mowing early in the
morning or even better, in the evening. Mowing during the heat of the day can cause the
plant to go into shock. Mow when the grass is dry. Your mower will work better and
there is less likelihood that disease will be spread from plant to plant.
Never cut off more than one third of the leaf tissue in one mowing. If you are mowing
your grass at 2 inches don’t let it grow over 3 inches. A drastic decrease in height can
shock the plant. This doesn’t mean you can let it grow to 4 inches and mow off 1 inch in
the morning and another in the afternoon. The plant will show the signs of this abuse.
Make sure your mower blades are sharp. Dull mower blades will tear the grass instead of
cutting it. This often creates a tan or brown cast to the lawn after mowing. Torn grass
blades are more likely to get infected with a fungus than properly cut grass. Check the
turf after mowing to make sure your equipment is in good condition.
2 East Main Street  East Dundee, IL 60118 USA  1-800-405-TURF  www.TheLawnInstitute.org
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Leave clippings on the lawn. Clippings are full of nutrients and can actually reduce your
need for fertilizers. Grass clippings readily breakdown and will only cause an issue if the
quantity is excessive. Mulching mowers are great at making the clippings small enough
but even standard discharge mowers will not cause a problem if you are following the
one third rule.
Mowing often lays the grass over slightly (this is how the patterns develop) and it is
important to mow in a different direction often so the grass does not lie over excessively.
Changing the pattern can also reduce wear and compaction by changing the areas that are
traveled.
Recommended Mowing Heights
Kentucky Bluegrass
2-3 inches
Tall Fescue
2-3 inches
Perennial Ryegrass
2-3 inches
Fine Fescues
2-3 inches
St. Augustine grass
1.5-3 inches
Bermuda grass
0.5-1.5 inches
Zoysia grass
1-2 inches
Centipede grass
1-2 inches
Buffalo grass
3-4 inches
Mowing Heights Effect Lawns
It is always best to maintain these grasses at the top end of these height ranges. Longer
grass will shade the soil, keep it cooler and reducing evaporation. This shade also
reduces the opportunity for weed seeds to germinate. Shortly mowed grass will have
much more weed pressure.
Think of the grass blades as solar panels for the plant and the roots are the energy storage
cells. Leaving grass blades long increases the size of the solar panels and results in
greater energy storage and root growth. Root growth is often directly proportional to top
2 East Main Street  East Dundee, IL 60118 USA  1-800-405-TURF  www.TheLawnInstitute.org
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growth. The longer the grass blades the deeper the roots; this allows grass to find water
and nutrients at greater depths.
It is often thought that if you mow the grass shorter it will allow for a longer duration
between mowing. This is untrue. Shortly mown grass wants to rapidly grow back what it
has lost. The grass will pull reserves from the roots to increase shoot growth. This
decreases rooting and increases the chance the lawn will show signs of drought or heat
stress.
The only time mowing short is advocated is late in the fall in those climates that see snow
or temperatures below freezing for over 30 days. Mowing short this last mowing will
reduce matting of the grass in the spring and decrease the chance of cool season fungal
diseases called snow molds.
Grass can be neglected to the point that it grows too long. Over a certain height grass
will not support its own weight and will begin to fall over. This can cause the underlying
grass to be smothered and die. This can also lead to excessive moisture being trapped in
the turf canopy increasing breeding of fungal diseases.
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2 East Main Street  East Dundee, IL 60118 USA  1-800-405-TURF  www.TheLawnInstitute.org
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