Do not mow your lawn for 4–8 weeks after you spread grass seed. Even if you are overseeding an already established lawn, wait until your new grass seed is mature before mowing. Mowing too soon can kill grass seedlings instantly. As a general rule, wait until the new grass has grown to a height of 3.5 inches (9 cm) before you mow it for the first time.
What are the Downsides of Mowing New Grass Too Soon?
Mowing grass too soon after it has been sprouted can kill your grass seedlings. Young grass has very small root systems. The suction of the mower blades can uproot seedlings by the hundreds, killing them.
- Mowing too soon will kill almost all of your new grass.
- The suction of lawn mower blades will uproot baby grass plants.
- Foot and wheel traffic will kill baby grass plants.
The wheels of your mower, as well as the pressure of foot traffic, can also crush grass seedlings, killing them. When possible, make sure to wait the correct amount of time before walking on your new lawn. Any and all traffic on new grass can be deadly to your crop of seedlings.
Does Cutting New Grass Help it Grow?
There is no upside to cutting new grass before it has developed strong roots. Instead of cultivating a lush lawn, you will end up with large quantities of dead grass. It’s essential for your new grass to mature to the point where it resembles the mature grass in your yard before you mow.
How Many Weeks After Seeding Can You Mow?
Plan to wait 4–8 weeks after seeding before you mow for the first time. Fast-sprouting, fast-growing grasses can sometimes reach mature heights in 4 weeks under optimal conditions, but this is rare. Most grasses require 8 weeks before they are ready to mow. In fact, some grass seeds take as long as 30 days to germinate after they’ve been spread. Patience is the key when growing new grass.
- Allow 4–8 weeks for your new grass to grow before you mow your lawn.
- Most grasses require 8 weeks after planting before they can safely be mowed.
- Check your grass—short, thin blades that pull out easily cannot survive mowing.
Whether you are growing warm-season grasses or cool-season grasses, it’s essential to observe your yard to know when it’s time to mow. If the new grass blades you see are thin, spindly, and easily uprooted when you tug on them, they’re not ready for mowing.
Can You Mow a Week After Overseeding Your Lawn?
Never mow one week after overseeding your lawn. Many species of grass seed will not sprout within a week of being spread. Mowing at this point will scatter the grass seed and destroy your hard work overseeding. Even if your grass seed has sprouted, it’s far too delicate to mow within one week. You will kill your new grass seedlings by mowing too early.
How Long Should You Let New Grass Grow Before Cutting It?
Allow your new grass to reach a height of 3.5 inches (9 cm) before you mow it for the first time. Then, mow your lawn to a height of 3 inches (7.5 cm). It’s important to let your grass grow tall before mowing so that it develops strong roots.
- Wait until your new grass reaches 3.5 inches tall (9 cm) before mowing for the first time.
- Cut your grass to a height of 3 inches (7.5 cm).
- Do not cut more than one-third of the grass blade when mowing.
- Determine when it’s time to mow based on the height of new grass—ignore the height of any previously established grass.
It’s essential to cut off no more than one-third of the grass blade when mowing. Cutting new grass too short is the quickest way to kill it. Even if you have overseeded your existing yard and your old grass is getting long, wait to mow. Judge if your lawn is ready based on the progress of your new grass, not the old grass.
How Soon Should You Mow After Planting Grass Seed?
If you have recently planted grass seed, follow these rules to mow it at the right time.
- Wait at least 4–8 weeks before mowing after planting grass seed.
- Most grass species require 8 weeks before they are ready to be mowed.
- Make sure your new grass is at a height of 3.5 inches (9 cm) before you mow it for the first time.
- Never cut off more than one-third of the grass blade when mowing.
- Mowing too soon can kill new grass.
These rules apply to both cool-season grasses and warm-season grasses. As a rule, it’s better to judge whether your grass is ready to mow based on its height, not how much time has passed since planting. Environmental conditions can cause some new grass to grow more slowly. If you judge when your grass is ready for its first cut based on height, you’ll get it right every time.