When should I start mowing a newly seeded lawn?

Question:

When should I start mowing a newly seeded lawn?

Answer:

The new grass should be mowed when it is 3 inches tall. Make sure the mower blade is sharp. Mow at a height of 2 to 2.5 inches. Mowing at this time will promote the spreading and thickening of the grass. 

New lawn grasses should not be allowed to grow excessively long before the first mowing. If the new grass is allowed to reach a height of 4 inches or more, set the mower blade as high as possible and promptly mow. Gradually reduce the height of the grass in later mowings.