When to Mow New Grass

If all goes well with the seeding and germination process, you’ll reach the stage where your grass is growing taller by the day. In deciding when to mow new grass for the first time, timing is crucial; mow too soon, and you risk damaging and ripping up your tender seedlings.  

As a general rule, you should mow new grass when the new growth is 1 ½ times taller than the recommended cutting height for your species. This ensures the root systems are developed enough for the seedlings to withstand and recover from the mowing process. You need to wait for the grass to become fully established, which usually takes about 6 to 8 weeks after planting. 

This article explains when to mow new grass for the first time to promote the continued healthy growth of your overseeded or newly seeded lawn. We have also provided recommended grass cutting heights by grass species, as well as some guidance on how to safely mow your new grass for the first time.

How Long Does it Take Grass Seed to Grow?

Generally speaking, grass seed can take anywhere from 5 to 30 days to begin germination. Once they have finished germination, your seedlings should grow at a rate of about 2 to 3cm per week. Your grass will become fully established in roughly 6 to 8 weeks after planting.

The exact length of time it takes for your grass seed to grow depends on several factors; the time of year, weather conditions, and level of moisture in the soil all have an impact on germination time. Your new grass will need consistent levels of moisture and access to full sunlight in order to germinate and grow.

Also, germination rates vary between grass types, with cool-season grasses typically growing faster than warm-season grasses. It’s crucial to pick a grass species that will be compatible with your lawn and will thrive in your area.  

The age and quality of your grass seed will also affect the germination time of your new grass. You can store it for anywhere between 2 and 10 years before grass seed goes bad; however, the longevity of stored grass seed is heavily dependent on the conditions in which it’s stored. In terms of seed quality, lower quality seeds will have a lower germination rate than those from a high-quality source.

How to Get Grass to Grow Faster

To get your grass seed to grow as fast as possible, it’s crucial to take care at every stage of the growing process. 

Before you sow the seed, you need to properly prepare the soil in your lawn for planting. This involves testing the soil to find out the pH and nutrient levels it currently contains. You can then use the results of this test to determine whether you need to add any pH-adjusting materials or fertilizer to get your soil in optimal growing condition. The best practice is to spread 1 to 2 inches of compost across the planting area before tilling it into the top inch of the soil. Use a rake to level the seedbed by removing any rocks or debris in the area.

Once you have fully prepared your soil, you will then be able to plant the new grass seed. Use a seed distributor to spread the seed evenly throughout the planting area, following the seeding rate for your chosen seed. Rake the planting area to encourage an even distribution of the seed and to incorporate it better in the soil. 

Straight after sowing your seed, cover the planting area with a fine layer of straw; this acts as a mulch and protects the seed from being blown away or eaten by birds. Finally, use your feet or a lawn roller to compact the planting area down; this improves seed-to-soil contact which in turn will increase the likelihood of fast germination. 

After the grass seed germinates, you should avoid stepping or placing anything on the lawn for a minimum of 4 to 8 weeks. When the grass has become fully established, you will be able to mow for the first time – as we explain further in the following section.

a lawn mower mowing half cut grass

When to Mow New Grass

You can mow new grass for the first time after seeding when the grass reaches around 1 ½ times its recommended height. This will take a minimum of 4 to 8 weeks after germination, depending on the factors previously explained in this article.

Timing is crucial when it comes to mowing your new grass for the first time. In the first few weeks after planting, your grass seedlings are working hard to establish roots and grow leaf blades. Their blades are delicate at this stage and are unable to withstand the stress of the mowing process. 

If cut too soon, the grass plants will struggle to recover from the stress as their roots will be underdeveloped. Also, without established roots, the mower’s wheels and blades may rip up the grass seedlings completely. 

On the other hand, it can be detrimental to the health of the grass to let it grow too long before mowing. When cutting grass, it’s best practice to follow the ⅓ rule; you should never remove more than ⅓ of the grass’ total height each time you mow. So, if you let the grass grow too tall, you won’t be able to cut it down to its optimal height on your first mow. 

When to Mow After Overseeding

If you have overseeded your lawn in certain patches, you can continue to mow the rest of the mature grass following your usual mowing schedule. As your new seedlings grow and you keep mowing your mature grass, they will gradually blend together. Mow the overseeded patches for the first time when the new grass grows to be 1 ½ times its recommended height. 

If you have overseeded your lawn entirely, it won’t be possible to mow your lawn without disturbing your new seedlings. Hold off on mowing any part of the lawn for at least 4 weeks until the seedlings are fully established. Again, the new grass should be about 1 ½ times its recommended height before mowing for the first time. 

When to Mow After Laying Sod

You should be able to mow new sod about 2 weeks after laying it. You need to make sure your sod is well-rooted before mowing it for the first time. If you mow too soon, it puts too much of a strain on the new sod. The root network is unable to support the grass plant’s recovery from this stress, which ultimately results in damaged turf. 

You can check whether your sod is ready for its first mow by making sure that it has rooted properly. Gently tug on a corner of the sod; well-rooted sod shouldn’t shift, so any movement indicates the sod isn’t ready yet. Wait a few more days, then repeat the test, doing so until you stop feeling movement in the sod.

As an additional tip, reduce how often you water the new sod before the first cut. This will help the soil to firm up before you mow, and encourages the grass plants to grow deeper roots. Let the ground and plants dry out before mowing sod for the first time. 

How Tall to Mow New Grass

The best height to cut your new grass will depend on the type of grass you’re growing. Each grass species has its own ideal cutting height, with most falling in the range of 1 ½ to 2 ½  inches. See the table below for the recommended mowing heights and mower settings for several common turfgrasses:

Grass SpeciesMow When Grass Reaches this Height in InchesSet Mower to this Height in Inches
Annual Ryegrass2 ¼ to 31 ½ to 2
Bermudagrass (Seeded)1 ½ to 2 ¼1 to 1 ½ 
Bermudagrass (Hybrids)¾ to 1 ⅛ ½ to ¾ 
Buffalograss1 ½ to 31 to 2
Centipede2 to 31 ½ to 2
Colonial bentgrass¾ to 1 ½ ½ to 1
Creeping bentgrass¾ or less½ or less
Dichondra¾ to 1 ⅛ ½ or less
Fine fescue3 to 3 ¾ 2 to 2 ½ 
Hard fescue2 ¼ to 3 ¾ 1 ½ to 2 ½ 
Kentucky bluegrass2 ¼ to 3 ¾ 1 ½ to 2 ½ 
Kikuyugrass1 ½ to 2 ¼ 1 to 1 ½ 
Perennial ryegrass2 ¼ to 3 ¾ 1 ½ to 2 ½ 
Red fescue2 ¼ to 3 ¾ 1 ½ to 2 ½ 
Rough bluegrass1 ½ to 3 ¾ 1 to 2 ½ 
St Augustine grass1 ½ to 31 to 2
Tall fescue2 ¼ to 4 ½ 1 ½ to 3
Zoysiagrass¾ to 1 ½ ½ to 1

The general advice for mowing grass at any stage is to always follow the ⅓ rule. This rule dictates that you should never remove more than ⅓ of the grass’ total height each time you mow. Working backward from this, you want your new grass to be roughly 1 ½ times its recommended height before mowing.

When mowing new grass for the first time, you should allow it to grow to the highest end of its recommended height range. This will give the grass the best chance at becoming well-established in the soil before your first mow. 

How to Mow New Grass

We have gone through the steps you should take when mowing your new grass below.

1. Wait For the Right Conditions

As we’ve explained, you first need to wait until the grass is 1 ½ times taller than the recommended cutting height for your species before mowing it for the first time. You also need to wait for the right conditions to mow, i.e. a day where the weather is forecast to be warm and dry. 

Avoid mowing the lawn right after rainfall or if you have recently watered. Mowing a wet lawn is a bad idea for several reasons; it may damage the soil and grass plants, cause your lawn mower to die, and cause the spread of lawn fungus. It’s also more difficult to safely mow wet grass and will ultimately leave you with an uneven lawn. Therefore, allow your lawn to dry out before attempting to mow for the first time. 

One of the best times to mow your lawn is in the mid-morning, between 8am and 10am. Any earlier than this, and the grass may still be damp from dew, rain, or irrigation water. By 8am, the grass should be dry enough to mow and has enough time to recover before the day’s heat. 

Alternatively, the other best time to mow is in the late afternoon, between 4pm and 6pm. At this time of day, the temperatures are milder and the grass has enough time to recover before nightfall. This protects the grass from being vulnerable to the development of lawn fungus overnight. 

2. Sharpen Lawn Mower Blades

Having sharp mower blades is good practice when mowing your lawn at any time. It is particularly important when mowing new grass for the first time to prevent stressing out the young grass plants. 

When you mow with dull mower blades, the mower has more of a ripping action on the grass. As a result, the mower tears the blades rather than getting a clean cut. This weakens your grass blades and leaves them more susceptible to the development of fungal diseases. Therefore, mowing with sharp mower blades is essential for the health and growth of your grass.

Before mowing your new grass, check that your mower blades are sufficiently sharp. As a general rule, you should sharpen your lawn mower blades after every 20 to 25 hours of usage. This will work out at about one to two times per mowing season for most homeowners.

You can have your blades sharpened at a hardware store for a fee. Alternatively, you can sharpen mower blades yourself at home if you have access to a hand file, blade sharpener, or angle grinder. If sharpening your blade yourself, make sure to check the blade balance before replacing it in the mower.

3. Set Mower Height

Make sure that your mower is set at the right height for how tall you intend to cut the grass. You may need to adjust your mower deck to set it at the best cutting height for your grass type. If you’re unsure what height this would be, refer back to the table earlier in this article which lists the recommended mower height settings for most common turfgrasses.

4. Mow Grass

When the conditions are right and your mower is set, you can mow your new grass for the first time. Ideally, you should use a lightweight push mower on your new lawn. Other heavier types of lawn mowers may create divots in the soft turf and their tires can compact the new grass.

When mowing, move slowly across the lawn and turn gently to avoid disturbing the new seedlings. If you mow too quickly, you risk ripping up the seedlings from the soil; their roots are less developed and are less capable of anchoring the grass plants under the stress of mowing.

5. Deal with Grass Clippings

After mowing, you can leave your grass clippings on the lawn – as long as they aren’t clumping together. If left on the lawn, the grass clippings will gradually decompose and release nutrients back into your soil. They act as an organic nitrogen-rich fertilizer for your grass, as well as helping the soil to retain moisture. Give the grass clippings a rake to spread them out evenly. 

However, if the grass clippings are clumping together, you should remove them from the new lawn. A thick layer of damp, matted grass clippings may end up suffocating your young grass. Bag the clippings and add them to your compost pile or use them for other purposes around your home. 

Also, it’s best to remove the grass clippings if you noticed a lot of weed growth during seeding. Avoid placing these clippings on your compost pile so as to not inadvertently reintroduce the weeds back into your soil. 

6. Repeat 3 to 5 Days Later

Wait for 3 to 5 days after your first mow before mowing the lawn for the second time. From this point onward, you should keep up with a regular mowing schedule. This will likely see you mowing every 5 to 7 days throughout the growing season. 

As a tip for your concurrent sessions, you should change up your mowing pattern each time you mow. This helps to prevent tire ruts from forming in the lawn as a consequence of mowing in the same direction. You can mix up your mowing sessions between using a horizontal, vertical, and diagonal mowing pattern to avoid this. 

grass plants growing in soil

More Aftercare Tips For New Grass

Fertilizing New Grass

The first fertilization that you should carry out on your new grass is an application of starter fertilizer during seeding. Starter fertilizer contains all of the nutrients that your grass plants need in the earliest stages of germination. You can apply it either immediately before or after sowing your new seed, before tilling it into the planting area. 

When the grass has matured, you can move on from starter fertilizer to regular fertilizer. This second fertilization should take place about 4 to 6 weeks after you see the grass sprouting from the soil. 

It’s best practice to first test your soil to determine whether it’s lacking any nutrients in particular before fertilizing. The results of this test can help you decide which fertilizer you need for your lawn’s specific needs. Generally speaking, the best type of fertilizer to use on mature grass is an organic, slow-release formula. While synthetic fertilizers work more quickly, they are more likely to lead to fertilizer burn and harmful chemical runoff. 

Watering New Grass

Watering requirements for new grass differ depending on whether you’re watering a newly seeded or newly sodded lawn. 

If watering an overseeded or newly seeded lawn, you will need to keep the planting area consistently moist throughout the germination period. This typically involves irrigating 2 to 3 times per day for 10 to 15 minutes each time. Aim to keep the top 1 to 2 inches of soil consistently moist until all of the new seed sprouts. 

If watering a newly sodded lawn, you should water the sod thoroughly within the first half-hour after installation. Add enough water so that the top 3 to 4 inches of soil are moistened to prevent the sod from drying out. For the first week after installation, you should water new sod daily; you will likely have to water 4 to 6 times throughout the day for 5 minutes each time. After a couple of weeks, you’ll be able to reduce this amount to one session a day. 

Troubleshooting Common Issues with New Lawns

Mushrooms and Toadstools on New Lawns

One of the most common issues you may encounter with your new lawn is the growth of mushrooms or toadstools. They appear after healthy soil has been disturbed during the seeding process, bringing dormant fungal spores to the soil surface. On top of this, you need to keep the planting area consistently moist throughout the first few weeks of germination; this provides the fungal spores with the perfect conditions to grow into mushrooms or toadstools. 

The majority of lawn mushrooms aren’t poisonous and will go away on their own with time. However, you may wish to get rid of them sooner if they’re ruining the aesthetics of your new lawn. You can run the lawnmower over them to break them up, or alternatively remove them by hand. After they go through two or three flushes, the mushrooms should disappear on their own completely. 

Fungal Lawn Diseases on New Lawns

Another issue you may face with your new lawn is the development of lawn fungus. Again, this is a problem that can arise from keeping the planting area consistently moist in the first few weeks. Lawn fungus thrives when conditions are warm and damp. Your lawn is also more susceptible to fungal infestations if you mow the grass too short. 

There are many different types of lawn fungus that present in different ways on your grass. In general, the typical signs of a lawn fungus infestation are expanding patches or rings of discolored grass, grass blades that have a powdery or threadlike coating, patches of grass that appear wet or slimy, or patches of dead grass. 

To tackle lawn fungus on a new lawn, make sure that you’re only adding as much water to the planting area as absolutely necessary. Cut back on watering if your seedlings are past the point of germination and strong enough to cope with less irrigation. You can also apply a systemic fungicide to kill the fungal spores and stop them from spreading any further in your lawn. Make sure to choose an appropriate fungicide for the type of fungus you’re dealing with. 

Weeds on New Lawns

It’s also very common to see weed growth in a newly seeded or overseeded lawn. When you turn up the soil in preparation for seeding, you also turn up weed seeds to the soil surface. With access to light and water, these weed seeds will germinate alongside your new grass. 

You shouldn’t worry too much about these weeds, as the grass will outcompete most of them as it matures. If you’re desperate to get rid of them, you won’t be able to do this with a weed killer straight away; most weed killers will damage grasses that are under three to six months old. You can look at the packaging of weed killer products for guidance on when they’d be safe to use on your new lawn. In the meantime, keep an eye out for any large, obvious weeds like dandelions, and pull them up by hand.

Pests in New Lawns

Pests are also common problems for new and mature lawns alike. The most destructive pests to new lawns are grubs, chinch bugs, cutworms, and armyworms. Their feeding habits can cause extensive damage to grass and can weaken your otherwise healthy lawn. 

Unlike herbicides and fungicides, you can safely apply most pesticides to a new lawn at any stage of growth. Check the label of your chosen product for exact instructions on how to safely apply it. 

Similar Posts