New lawns require special care during the establishment period. Like all seeds, germinating grass seeds tend to be fragile. Damage to new lawns often occurs during the early stage of seed establishment. Knowing when to mow and water, as well as the correct cutting procedures, produces strong, healthy growth in newly planted lawns. Homeowners may have to wait up to two months before mowing the lawn after seeding.
Check the growth of your new grass seed. Look for bare spots and thin spots, indicating slow germination. Individual grass seeds germinate at different rates, especially in lawns seeded from seed variety mixtures. Wait to mow until the majority of grass seedlings show signs of strong growth and maturity in all areas of your lawn.
Measure your grass blades with a ruler. Wait until the average height of the grass blades reaches a minimum of 3 inches. The recommended height for different grass varieties varies, depending on type and landscape uses. Allowing your grass to grow to the high end of the recommendations for your grass type encourages healthy root growth in new grass.
Wait until the grass is dry to mow the first time. Avoid watering prior to the initial cutting to avoid wet grass that may tear or clump. Plan ahead when determining your mowing pattern to avoid excessive traffic over your new lawn during the mowing process. Place a bag on your mower to catch clippings as you cut the grass. This avoids additional traffic from raking after mowing.
Set your lawn mower height to cut less than one-third off the length of the grass blades. Most lawn grasses require an average cutting height that leaves 2 and 3 inches of blades above the ground. This is a good length once the lawn is established. However, this initial cutting requires longer blades of grass to avoid damaging new grass grown from seeds.
Mow a second time a few days after the initial mowing, setting the blade height slightly lower to create a gradual decrease in grass length to obtain the desired lawn height. This practice avoids shocking new blades by limiting the amount cut at one time. Maintain the desired height during subsequent cuttings of your lawn.