Gardeners given heatwave lawn mowing warning

Mowing the lawn
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Mowing your lawn in hot weather is likely to damage your lawn, with long-lasting effects, according to experts. The much-promised heatwave has hit this week and millions of Brits will want to be outside enjoying their gardens.

Many will be tempted to mow their lawns so they look smart for the summer weather. But experts from have warned Brits not to mow in extreme heat, due to the damage that is highly likely to ensue.

Mowing grass when it is too hot can lead to unsightly brown patches or if the grass is killed, bare patches in your lawn. Leaving your lawn longer helps protect the blade and keep the moisture in the grass while the weather is warm.

Gardening expert James Lewis from, said: “It’s understandable that we want our gardens to look smart while we enjoy them in this warmer weather. However, mowing lawns in the heat can do damage that lasts for way longer than this heatwave. If it’s cut too short it will expose the blades to more heat than they can handle, potentially killing them.

"This will lead to bare patches in your lawn which will take time and effort to repair. Best to leave your lawns, the extra length will help protect them until the heatwave is over, and there are other tactics you can use to help keep your lawn healthy.”

Looking after your lawn during hot weather


Let it grow

Letting your grass grow a little longer allows it to cope with heat stress. Longer grass in hot weather acts as a “micro jungle”, with taller stems helping to sustain a microclimate at soil level. When temperatures rise, mowing can actually cause stress to a lawn so it’s often best to leave your grass to grow a little longer in these conditions. A good guide for the average lawn would be to keep the length to something around the 2.5cm-5cm, although if you wish to grow it a little longer then up to twice that height can promote healthy blades of grass.

Raise your mower

To avoid scalping the lawn, the cutting height of your mower should be increased during dry conditions. The majority of lawnmowers have different height settings and a higher setting will allow valuable moisture to be trapped, limiting evaporation and encouraging stronger, deeper roots to grow, which improves drought tolerance overall.

Create a wild garden

Wild gardens are better at coping with drought. You need to water it less and you’ll have a bit more green, but you're also supplying a rich nectar source for all the bugs and pollinators, in turn helping the environment.

Be prepared to water

If you need to mow your lawn when it’s hot, be prepared to regularly water it. It’s ideal to water lawns about one inch of water per week. If using a sprinkler, it will take approximately 30 minutes to get a half inch of water. There are a variety of techniques that can be used to water your lawn, from a handheld watering can with a sprinkler head, a sprinkler, an irrigation system or a hose pipe. It’s important not to overwater, so while daily watering may not be needed, regular watering is the best way to avoid burning the lawn by ensuring there is adequate moisture in the soil.

Provide shade

Planting trees or installing shade structures in your garden will provide some much-needed relief to your lawn during hot days. Shade helps to lower water loss through evaporation which in turn creates a cooler microclimate, reducing the need for frequent watering while maintaining grass health. There are many different options to add shade to your garden including awning, parasols, sail canopies, pergolas, arbours, and gazebos for planting trees or tall shrubs. The best option for you will depend on your garden size, type and the budget you have available.


Get heatstroke

In hot weather, everyone should avoid extreme exercise as this could lead to heat exhaustion or heat stroke. Mowing a larger lawn in extreme heat could be exhausting, so avoid it if you can, and if you have to ensure you only mow early morning or late evening when the temperature is lower. If you do need to do mowing or any gardening when hot then ensure you have applied sun cream, are wearing a hat and take regular breaks to take on water.


One of the worst things you can do for your lawn when it's hot outside is to over-mow it. The shorter the grass, the less shade there is to protect the roots and therefore the amount of moisture held by them is reduced - grass that is too short will dry out. When mowing your lawn it is good practice to follow the one-third rule by never cutting more than a third of the blade of grass in one go. If you cut more than a third this can stress the grass and affect its growth

Water your lawn when it's sunny

Watering your lawn when the sun is hot and shining directly on it can cause damage. Blades of grass will normally only grow during the cooler part of the day. Watering is always best done either early morning before 8am or at night after 9pm when grass can grow, and be able to take the water and not evaporate. You can set timers for your irrigation systems and sprinklers to activate during these best watering times, or ensure you do it manually at these times.

Waste water
A great tip is to utilise 'grey water' for irrigation, repurposing water from activities like vegetable boiling or bathing to conserve water resources. Adding a water butt or rain collector is another great way to save water and reduce your impact on the environment. However, ensure that the water does not contain harsh chemicals or human waste to maintain the health of your grass and soil.

Forget to re-seed

It’s crucial that you don’t forget to re-seed and fill in bare spots in your lawn with grass seed to maintain a dense turf cover. This will help reduce water loss through evaporation whilst also helping to prevent soil erosion. The ideal times to overseed lawns are in springtime from March to early May, and then late summer into early autumn from the end of August into September.