When to Mow New Grass: Lawn Care Guide

When you decide to first mow your new lawn is critical to its chances of success.

It can be hard to know when it’s okay to start mowing a newly laid lawn.

After watering and fertilising your new grass, the next step is deciding if you should cut it or wait.

Why the first mow is important

Lawn mower 1 | Lawn care

The first mow is the most important.

When you decide to first mow your new lawn is critical to its chances of success. If you mow too soon or too short, you may damage it to the point it won’t grow back properly.

When to first mow a new lawn

You need to wait until your grass is established with firmly rooted, healthy growth.

When your lawn is a few weeks old, check if it is growing well and look at how long the blades are.

You should generally wait until they’re around 6cm (2.4 inches) tall before you give them their first trim. However, the time this takes will depend on whether you grew your grass from seeds or as turf.

If you used seeds for your new lawn, it could be several months before your first mow.

But don’t think about mowing for too long. Long grass doesn’t grow as evenly as shorter grass and is more susceptible to weeds and pests.

Also, try not to mow in wet conditions; this may damage your grass and make mowing much harder work for you.

What happens if you mow a new lawn too soon?

grass | Lawn care

While mowing your new lawn is an exciting milestone, it’s important to wait until the right time.

When you mow too soon, you can damage your new grass and leave it susceptible to water loss, nutrient deficiencies, and infestation.

What’s more, if you cut the grass too short or when it’s wet, you can even kill your new lawn.

What happens if you leave it too long to mow a new lawn?

lawnmower 1 | Lawn care

If you wait too long to mow your new grass, you may get weeds, pests and diseases.

When the grass gets too tall, some blades of grass become shaded by others.

When this happens, the leaves lose their ability to absorb sunlight, which helps them grow healthy and strong.

It also reduces the number of healthy roots, which means they lose their ability to absorb water and nutrients from the soil.

What height to first mow your lawn

The optimal height for your first mow will be determined by the variety of grass you are growing.

However, as a general rule, aim to never cut off more than 1/3 the height of each blade of grass. Your cutting height will likely be around 3cm.

This is important, because if you mow at a lower height, then your lawn may not be able to absorb enough sunlight. It may also become more prone to weeds and disease.

Some grasses can handle being cut short, while others perform better when they have time to grow taller.

Ensure your mower blades are sharp

lawnmower 2 | Lawn care

Unsharpened lawn mower blades will tear the grass and leave behind a ragged appearance. Those tears in the grass are space for disease to move in—and it could cause your lawn to turn brown by summer.

If you want to sharpen your own mower blades, use a file or an angle grinder to remove nicks and smooth the edge of each blade.

Then hone the blade by rubbing with a sharpening stone.

You can also get your local hardware store or lawnmower repair shop to sharpen your mower blades if you don’t own sharpening tools or don’t feel comfortable doing it yourself.

You’ll need new blades if they are cracked, have deep gouges or show any significant signs of wear and tear.

Other mowing tips

  • If you’re unsure of when to mow your lawn, ask the lawn supplier.
  • Mow in the morning or evening. Avoid mowing in the heat of the day because lawns are prone to disease and stress during this time. You also don’t want to mow your lawn when it’s wet because it can damage your equipment and clump up the grass. Also, new lawns are more prone to damage when wet – cutting wet grass will cause ruts and tear up your lawn’s newly forming turf.
  • Mow regularly to help keep weeds under control. And make sure you mow only a third or less of the length of each blade at one time. So if your grass is 10-15cm tall, only cut off 3-5cm max at any given time.

Other tips for new grass

  • Set your mower to a high setting and then gradually lower it as the weeks go by. For instance, you might cut a brand-new lawn at 3″ instead of 2″. Gradually lower that to 2″ as the ground gets tougher.
  • Mow in different directions each time you cut; this prevents rutting and makes for a healthier lawn overall.
  • Leave some clippings on the lawn (unless there is an excessive amount) since these provide nutrients for newly planted turf seeds as well as fertilizer for existing grass plants.
Photo of author

Steve Kropp

Based in Melbourne, Steve's passion is vegetable gardening, and he’s been writing about it for almost 5 years. He also loves all things DIY and is always looking for a new project. When not working on his own garden projects or blogging, Steve enjoys spending time with his family, cooking meals with produce harvested from his garden, and coaching his son’s footy team.


Leave a Comment