Mow High

Because of the heat and drought of summer, I set my mower high. (The highest setting on the Black and Decker CM1936 is 3 1/2 inches. This means that I can let the lawn grow to a height of 5 1/4 inches and still safely mow it, without fear of damage to the grass.)
  

This is the overall look.

  
Then this happened

My next door neighbor mowed this section of my lawn.  (Search for neighbor mows my lawn to see that this is a common problem). His mower was set low, and he scalped right down to the ground.
This occurred on August 12.

What is scalping?

Scalping occurs any time more than 1/3 of the grass blade is removed.  When that happens, the grass plants are unable to produce food through photosynthesis.  The plant draws energy from the roots in an attempt to recover.

In this case, the scalping was severe; cut right down to the ground.  The soil is not shaded by the grass, so it dries quickly in the hot sun.

Repair

I immediately removed the clippings he left, and began watering.  I never water my lawn, but this severe damage called for urgent care.

  
Day 1, August 13

Still bare ground. Watered again.
  

Day 2, August 14.  Watered again.
 

Day 3, August 15

  

Closeup of the new blades of grass trying to grow.

  

 
Day 4, August 16, 2015
  
Day 5, August 17.  Continuing to water.
  
Day 6, August 18.  Continuing to water. 
 

Day 7, August 19.
  
Day 8, August 20, 2015

Still watering every day.  There is some improvement, but full recovery might not occur until fall.

  

Day 9, August 21.

Real rain last night.

  
Day 10, August 22.

  
Day 11, August 23
  

Day 12, August 24

  
Day 13, August 25

  
Day 14, August 26

  
Day 15, August 27

Mowed last night at 3 1/2 inches. Still some bare spots, but starting to look better.