common grass species & best mowing heights
You will know it’s time to cut when your lawn is 1/3 taller than the grass’ normal height. The recommended heights below display the ideal height for the type of grass you are growing. Spring and fall bring cooler temperatures where you can maintain a shorter grass height. The heat of summer brings harmful rays to the soil where it can compact and allow moisture to evaporate. This is the time to maintain a taller grass blade. Below you’ll find your ideal lawn height.
Use the chart below to find a suggested height for your type of grass
| Grass | Spring | Mid-Summer | Fall |
| Bermuda | 1/2 inch | 1 inch | 1/2 inch |
| Fescue | 1 1/2 inch | 2 1/2 inch | 1 inch |
| Kentucky Bluegrass | 2 1/2 inch | 3 inch | 2 inch |
| Ryegrass | 1 1/2 inch | 2 1/2 | 1 inch |
| St. Augustine | 2 inch | 3 inch | 1 1/2 inch |
| Zoysia | 1/.2 inch | 1 inch | 1/2 inch |
Do It And How 
These heights look like they are for golf courses.
I live in the midwest and I keep my mower at 3″ all the time.
By the way, I have many types of grass–but since the lawn came with the house, I am not sure what all types of grass I do have.
We had that issue too… when we developed a bare spot it caused a concern of what type to buy and fill it in with.
Maybe this chart will help you:
http://www.american-lawns.com/grasses/grasses.html