When to Mow New Grass

Deciding to dig up an old lawn and start again, or turning over a patch of soil to create a lawn is a big decision. To get it right you must prepare the soil correctly, choose the correct type of grass for your situation and, most importantly, know when to mow new grass. If you get all this right, then a lawn is a great low maintenance landscaping choice.

If you are struggling to know when to mow new grass, this guide will take you through everything that you need to know.

1 When to mow new grass

Knowing when to mow new grass need not be difficult. 

Starting a Lawn from Seed

You can start a new lawn either by laying turf or sowing seeds. While starting from seed takes longer it is often more affordable.

Before sowing the seeds take the time to dig over and weed the soil. There are a number of good tools outlined here that can help you to completely clear the area of weeds. If your base soil is heavy or clay, work in amendments to improve and lighten it before sowing your grass seeds.

Rake the soil over before sowing the seeds. Rake the seeds in before compacting the soil down. This ensures most of the seeds stay in place and root. How long it takes seeds to germinate can vary depending on what type of seeds you have sown. In general seeds can take anywhere between 5 and 30 days to germinate.

Applying some lawn fertilizer before sowing also helps seeds to settle and germinate.  Usually germination is quicker in warm or light positions. Additionally, keeping the soil moist helps to boost germination. 

When to Water

Moisture plays a key role in getting your seeds to grow. It also affects when to mow new grass. Watering correctly encourages growth and root development. Start off right and your lawn will thrive.

Regularly watering the soil and seeds helps to soften the shells. This makes it easier for roots to break through, increasing the chances of seeds successfully germinating.

Additionally, fresh or young growth rarely has the root system to survive a dry spell. Continue to water your lawn regularly after germination to ensure lots of healthy, strong growth and deep roots. Deep roots are important because they affect how tall your lawn can grow. 

2 Water regularly
A hose or sprinkler is a good way to soak both the lawn and the soil beneath it. 

Use a hose to keep the soil moist. Too much water can drown the seeds. However, too little water can lead to the soil and seedlings drying out and failing. This means that it is important to get the amount of water you give your lawn right. Try to keep the top inch of soil evenly moist. In warmer or sunny positions this may mean watering as frequently as twice a day.

Continue to water your seeded lawn at least once a day until after the first cut.

Starting a New Lawn from Turf

As with growing from seed, preparation is the key to success. Prepare the soil, weeding and flattening it before laying the turf.

3 Starting from turf
Starting a lawn from turf may be quicker than growing from seed but it still requires regular care. 

For the first 2 weeks freshly laid turf is particularly vulnerable. Until roots grow and establish themselves, the turf can only access water from the top few centimeters of soil. This means that you need to water your turf at least once a day for the first fortnight. When watering ensure that you thoroughly soak the turf, allowing the water to soak down into the soil. During hot spells you may need to water the turf twice a day.

To check how wet the soil is, lift a corner of the turf. The soil beneath the turf should be wet but not sodden. Overwatering can drown and kill the turf.

Regularly watering turf can take a lot of water. Harvesting your own rainwater, for use in the garden, is a great way to keep your water usage down.  

After a week to 10 days the turf should begin to root. As roots form, you can gradually reduce the amount of water you apply. First, reduce watering to once every other day. After 4 weeks you should be watering the newly laid turf no more than twice a week.

Once roots have formed allow about 3 weeks of steady growth to develop before you reach for the lawnmower. To check when to mow new grass, tug the turf. If it lifts up, allow it to grow a little longer and for the roots to continue forming. If only a few clippings come away in your hand the lawn is ready for mowing.

When to Mow New Grass

Allow about 8 weeks of steady growth before you even consider mowing your fresh lawn. Don’t be tempted to mow new grass before it reaches 3 inches in height. Mowing too early means that you run the risk of ripping out the fresh growth, ruining all your hard work up to this point.


When you do mow new grass it is important that you follow good cutting techniques.

How to Mow New Grass

Almost as important as knowing when to mow new grass is knowing how to do it correctly. Get this right and you set your lawn up for a long and healthy life.

The first mow of new grass should be nothing more than a light trim.

Before cutting, ensure that the blades on your mower are sharp. Keeping the blades sharp helps to keep the roots deep and healthy. Ideally, lawnmower blades should be sharpened after 20 hours of use. This also applies if you are using long handled lawn shears.

Most local hardware stores sharpen lawnmower blades for a small cost. If you are serious about maintaining a lush, healthy lawn, then a Lawn Mower Blade Sharpener Kit is a worthwhile investment.

Before you start to mow new grass take the time to check the height of the blades on your mower. Aim to keep the blades at a good height. Following the ⅓ rule helps. The ⅓ rule is simply when mowing an established lawn, never remove more than a third of the blade height. So if your lawn is 6 inches long, don’t cut more than 2 inches.

Only cut your lawn when it is dry. Don’t cut the lawn after rain or watering. Wet grass blades can easily get torn or tangled in the blades. Wait for the lawn to dry to reduce the risk of it being pulled up by its roots. You should also avoid mowing the lawn during hot spells or if it is frozen.

4 Dont cut too heavily
When you start to mow new grass, don’t cut it too far down. 

For the first cut, set the mower on the highest setting. You should never remove more than 20% of the lawn with the first cut. This light cutting encourages more shoots to form at the base of the lawn, helping to thicken it.

Cut the lawn slowly, gently turning to prevent young delicate seedlings from being ripped up. Remember the young roots are still developing and are not as deep or strong as older or more established roots.

After mowing, clippings can be left in place as long as they aren’t clumping. This returns nutrients to the soil. Allowing clippings to remain on the lawn also helps the lawn to retain moisture. If seeding weeds are present you will need to bag and dispose of the clippings. Otherwise clippings are an ideal addition to the compost bin.

After cutting new grass for the first time, don’t let the lawn get really long and harshly cut it. This can be stressful for the lawn and may cause brown patches to appear. It is far better for the health of your lawn to cut it regularly.

Reduce the height of the lawnmower blades gradually over several cuts until you get to the ideal height. Remember to be gentle when cutting.

Once established, aim to keep your lawn roughly 3 inches tall. This height not only helps to keep the lawn and root system healthy but also crowds out any unwanted weeds. Some ryegrass based turfs such as Garden Lawn or Jubilee are designed to be kept at a height of 1.5 inches. Allowing them to grow slightly longer than this can make your lawn more durable and better able to cope with disease, drought and frost.

5 Mowing keeps grass healthy
Knowing when to mow new grass is key if you are aiming to grow a fresh, healthy lawn.

Remember to clean the mower after every use.

Alternate direction of mowing every time- if you cut from north to south one week, the next time cut from east to west. Regularly changing the direction helps to prevent graining. This is the term used to describe a lawn that seems to grow entirely in one direction.

Cheaper than artificial turf, laying a new lawn may be time consuming but your efforts are soon rewarded with a lush, green, maintenance lawn. Knowing when to mow new grass can be tricky. But if you get it right you can set your lawn up for a long and healthy life.

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