When do you cut a new lawn?




A Long New lawn with a mower in the middle

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Why you need to get this right. 

So you have got a new lawn and your thinking it will be due for a mow soon. 

If you haven’t done this before you may be a bit concerned. You want to get this right because you want a good looking healthy lawn. 

But when exactly do you do the first cut? 

In my 30 years in the industry, I have done my fair share of new lawns and there are a few hard and fast rules that you need to be aware of. 

So when do you cut a new lawn? A lawn can be ready for its first mow anytime between 4 to 8 weeks but there are a few simple things you can do to check if your lawn is ready

  • Is the grass over 4 inches high? – If so it will be ready for its first cut.
  • Pull in the tip of a piece of grass – If it rips off then it is ready. If the whole plant starts to come out then leave it for another week and try again. 
  • Look for a wave – I find the perfect time to mow a new lawn is just as the blade of grass starts to bend under its own weight. When you see the beginnings of a wave in your lawn it is time to cut. 

Now that you have established that your lawn is ready to mow, don’t go charging out there with your mower just yet. There are a few things that you need to do to give your lawn the best start and in optimal health. 

How do you cut new grass for the first time?

Here are four things you can do today to give your lawn a good start. 

Give your mower a quick wash

You want the inside of the deck to be as clean as possible. Remember if you have four-stroke life so that the spark plus is towards the sky (do not roll it on its side). Not sure if you have a two or four-stroke the read this. 

Make sure your blades are sharp. 

If your blades are too blunt then they tear rather then cut the grass. This causes damage and bruising on the grass and can also uproot tender new grass shoots. This will encourage diseases and fungi. You do not want this on your new lawn. 

Use sharp mower blades.

Set your mower to its highest setting

Your first mow needs to be high. Somewhere around 3 to 3.5 inches. Don’t take any more than 33% off the height of the lawn. 

There is something that all good gardeners follow called the rule of thirds. This means that you never take more than a third of anything. This includes trees, shrubs, and grass. 

Two new lawns. The one on the left is cut wrong (too short) and the one on the right is correct.
Two new lawns. The one on the left is cut wrong (too short) and the one on the right is the correct. (one of my lawns)

Make sure the lawn is dry. 

It needs to have been at least 48 hours since the last time it rained. The soil needs to be dry and not moist. If you are leaving tire tracks then the lawn is too wet. 

What can go wrong on your first cut?

If you do your first cut too early it doesn’t really matter how sharp your blades are. You are going to do damage to the lawn. The roots on the new grass need time to get established. If they are too shallow they can be pulled out by the mower as you mow resulting in a patchy lawn. 

If you leave the lawn too long before the first mow this is not so bad. Although the lawn will look terrible after the first mow, it should come right after the next few cuts. 

The first time it is cut you will need to cut it as high as possible. The main issue here apart from overworking your engine is that the grass will have nowhere to go. The shoot on most domestic mowers is no higher than about 8 inches at most. If your lawn is longer than that is is going to clog your shoot and you will only get a small percentage of the grass into your bag. It may be best not to have the catcher attached the first time around and rake up the excess grass.

You are also going to notice uncut lines in your lawn (i call these mohawks). They are caused by your wheels compressing the uncut grass as you mow. Double cutting straight away will not help because some of these pieces can take up the 24 hours to stand up again. The only real way to solve this problem is to recut a few days later. That will not solve the problem but it will help.  

If possible do another mow a few days later. 

If you cut it too short you can stress the grass and could cause die-off. Especially if the heat gets up shortly after the lawn is cut. The foliage that you have exposed is used to being covered and protected from the elements. The further you cut down the worse this can become. 

A short lawn can also encourage diseases and flat weeds so it is best not to go there. 

How should I look after the lawn in the future?

The best advice for a good looking lawn is mowing little and mowing often. Cut high and every time you mow the lawn change direction. This will prevent lawn mowing ruts and stop any lawn mowing patterns from showing in the lawn.

Clean the mower after each mow and keep your machine in good condition. Pay attention to the state of the blade and watch out for wear on the axel bushes that could make your mower cut unevenly. 

When do I mow and overseeded lawn?

If your lawn has been overseeded then you need to leave the whole area for about 8 weeks. 

Do make sure that you water it twice a day to keep the soil moist and a bit of fertilizer after the first couple of weeks will make a huge difference. The new grass is going to need to germinate and put down good roots before you cut it. 

I also prefer to mulch overseeded lawn as it helps feed the nutrients back into the soil and produces a healthier lawn. If you mulch that overseeded area it will turn back into lawn quicker. 

How often should I mow my lawn?

I have covered this elsewhere but if you are looking for cutting cycles for certain types of grass then you can find out with this guide from the University of California  UC Healthy Lawns—Mowing: How much, when, and how often to mow

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