Your Mower is Killing Your Lawn


By Rick Orr
St Augustine Lawn with RUler showing 5" canopy height
The canopy height is determined by measuring from the soil surface to tip of the leaf blade. Setting your mower so the canopy height is above 4” is best for St Augustine lawns.

Your mower kills your lawn by mowing St Augustine too short. St Augustine is a different turf than other lawn species - the stems and roots grow on top of the ground - like a ground cover instead of grass. When you mow your lawn so the canopy is less than 4" tall, the above-ground stems and roots are exposed to the harsh Florida sun, dry out and perish. A St Augustine lawn, to be sustainable (to survive, to be hardy, to thrive), must have a minimum canopy height of 4” - the higher the better.

How Mowing Too Low Happens

Appeal drives short St Augustine lawns. Many homeowners prefer a short lawn - low and level. To make a lawn level, all the grass must be the same height which forces you to mow the lawn at or below the shortest grass (the weakest, thinnest part of the lawn). At that setting, the entire lawn will be short but level.

Short St Augustine is Weak and Thin

The shortest grass is the weakest, thinnest part of the lawn – so mowing as low as the shortest grass dooms the rest of the lawn to the same fate - weak and thin. In the short term (after mowing), the lawn is low, level, and looks great. In the long term, after months of low mowing, the lawn declines into patches of dead spots, off-color, and full of weeds.

Your Lawn Does Not Grow Uniform

Some areas are wet, some dry, some shady, some sunny - causing the lawn to grow at different rates. This uneven growth makes for an uneven lawn. If the shortest part of the lawn is only 2" tall, to make the lawn level, you would mow the entire lawn at 2".

A Better Solution

Set the mower to the tallest setting and mow at that height. Although the lawn will grow at different rates, all the lawn will grow to a height of 4” to 5” – eventually.  Once the shortest grass reaches 4” to 5”, mowing at that height – 4” to 5” - will create a smooth level lawn that looks great and is sustainable.

4” Lawn - How to Get There

Growing a lawn to a sustainable height of 4” to 5” tall can be done in two ways: Option1) do not mow until the shortest part of the lawn is 4” to 5” tall or Option 2) set your mower to mow at 4” to 5” and mow on a regular schedule.

Option 1 is the easiest – just let your lawn grow until the shortest part of the lawn is 4” to 5” tall. This may take months depending on the time of the year and the lawn will be uneven with a lot of showy tall weeds. To mow the lawn, set your mower so the lawn is 4” to 5” tall (usually the highest setting) and mow the lawn. 

Option 2, set your mower to mow at 4” to 5” tall and mow the lawn on your regular schedule. It will seem odd that portions of the lawn are not being cut and the lawn will look uneven. Do not despair, eventually, all the lawn will be 4” to 5” tall, level, and sustainable.

A third option is to combine Options 1 &2 – when you can’t stand the look of the lawn, mow at 4” to 5” tall. This will keep the lawn more acceptable – not level but presentable - while the canopy reaches the 4” to 5”.

All three options require you to delay gratification and to suffer with an “uneven” lawn for a season or more. The upside is that once the lawn reaches the sustainable height of 4” to 5” tall, you will be rewarded with a better lawn - a lawn that is durable, hardy, greener, requires less water, and recover quicker from damage or stress.

Be Patient - Your Reward is a Better Lawn

The homeowner is most likely to delay gratification with the promise of a better lawn. Getting out of mowing the lawn and improving the lawn is a win/win for the homeowner.

The least likely to delay gratification is the professional - the mow guy. The professional knows that a level lawn looks best. They want the recognition of a good-looking lawn and the work from neighbors who see their “good” work. Raising the mower to sustainable heights will mean the lawn will be uneven and reflect poorly on their work.

How To Make the Professional Mow at 4" or Higher

Set a measurable standard. Here is a suggested standard: After mowing, the tallest part of the lawn must be 4” tall as measured from the soil surface to the tip of the leaf. You can reassure your mow guy this is what you want, and you understand that this may not be the best look after mowing. If the mow guy persists in mowing too low, refuse to pay for any mowing that does not achieve this minimum standard. Most professionals will quickly raise the mower to be paid.

Rick Orr Owner-Staff Agronomist Barefoot Grassl/Creator of ILOVETURF.COM
Staff Agronomist at Barefoot Grass

Since 1995, Rick Orr has worked in Pinellas County providing turf management and pest control. Rick Orr is a graduate of VA Tech in Agronomy (Turf Ecology) and the creator of 

Since graduating from VA Tech in 1979, Rick worked in the green industry, mostly with golf courses, resorts, and large communities. Rick has obtained certifications in arboriculture, landscape, irrigation, and taught Environmental Horticulture at St Petersburg College. 

Currently, Rick is the Staff Agronomist at Barefoot Grass in Largo, FL. To learn more about Barefoot Grass Free Price Quote from Barefoot Grass for Home Pest Control and/or Lawn Care 

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