Nearly all lawn mowers these days have adjustable cutting heights. You might see mowers with an advertised mowing height of between 30-75mm, for example.
This raises the obvious question – how high should you cut your grass?
In this buyer’s guide, we’ve explained what height you should cut your grass in the UK, at different times of the year.
What height should I cut my grass in summer?
In the summer, your grass will likely grow quite quickly, as there is plenty of warmth in the air, as well as decent rainfall, in many parts of the UK. This growth can accelerate into autumn, as many cool-season grasses still grow quickly as the air becomes cooler.
However, at the same time, you want to protect your lawn’s root system from getting too hot. You also want to avoid stressing out your grass in case the weather dries up.
Therefore, you actually want to be keeping your lawn a bit longer. In the summer, a good rule of thumb is to cut your grass about 5-6cm tall – or about 2 inches tall – in terms of an ideal grass blade height.
The height that you cut your grass should also depend on its health, and how fast it’s growing. If your lawn is extremely healthy, and is growing well, you’ll be fine to cut it down to 2cm tall. However, if your grass has issues such as thatch buildup, or is newly-laid, and isn’t growing quickly, then you may want to leave it a bit taller than 6cm to give it more of a chance to grow.
What height should I cut my grass in spring and autumn?
In the spring, you can also cut your grass quite short – around 3-4cm is best. This is because cool-season grasses, which are common in the UK, grow fastest when the soil temperature is around 15-24°C. The cool spring air helps to accelerate growth, and you can afford to cut your grass shorter without having to worry about the roots baking in the sun.
In the autumn, you should also cut your grass about 3-4cm tall. However, you do not want to leave your grass short going into the winter. The longer the grass, the easier it finds life in hibernation, because longer grass provides more protection against frost for the root system.
When you do your final cut before the winter, an ideal grass height is about 4-5cm tall, or even taller. This will help your grass to stay healthy while it’s dormant in the winter.
When should you not cut the grass?
In most parts of the UK, your grass will become dormant in the winter. It won’t grow much during December, January, and February, and will return to normal as the weather warms up.
Also, mowing your lawn when it’s wet, or when there’s frost can cause damage to your lawn.
Therefore, it’s best to avoid grass mowing during the winter months. Wait for the lawn to visibly begin growing again before you get out your mower for the first time.
Other lawn mowing height tips
If in doubt, always mow your lawn higher, rather than lower. This reduces the chances of you stressing out your lawn by cutting the grass too short, known as “scalping” it. The lower the roots, the less chance of photosynthesis occurring, which can affect root growth, impacting the health of your lawn.
You generally never want to take off more than a third of the mowing height of the blades at a time, for the same reason. If possible, it’s best to mow your lawn as often as possible with a high mowing height, but only when the grass has grown a certain amount, rather than every week or two weeks. Grass growth is your lawn’s way of telling you it’s ready to be cut. But don’t let your grass grow too tall, or you may stress it out when you do eventually cut it back down.