Gardeners have been warned that making one common mistake during summer could quickly turn a healthy green lawn into a patchy yellow mess. Experts say cutting your grass too short, also known as “scalping”, can cause serious damage, especially during hot or dry weather. While many people think shorter grass looks neater or reduces how often it needs mowing, the opposite is often true when it comes to lawn health.

Keeping your grass too short weakens it, dries it out faster, and makes it more vulnerable to heat, pests and disease. That’s why gardeners are being urged to raise their mower blades during warmer months and avoid cutting more than one-third of the grass height at a time.

According to lawn specialists at TruGreen, scalping “stresses your turf and can result in poor growth, bare spots, or visible damage”. 

They recommend mowing higher in summer to protect roots and reduce water loss. 

Experts at Stewart’s Lawn Service added that very short grass has a “weaker root system” and “may burn” when exposed to sun and high temperatures.

Even if your lawn looks fine right after mowing, yellow patches may appear a few days later as the grass struggles to recover. 

The Lawn & Weed Expert said this is often caused by a lack of moisture and stress from mowing too short, especially during hot spells.

They advise against mowing in the middle of the day and recommend cutting only when the lawn is dry.

Temperature is also important. Experts at Woman & Home warn that mowing during a heatwave, especially when temperatures hit 32C or higher, can cause “brown patches, root stress, and even long-term damage”.

To prevent yellow grass, most lawn care professionals suggest following the “one-third rule”. 

This means only removing one-third of the grass blade at a time, and using sharp mower blades.

Dull blades can tear rather than cut the grass, adding even more stress and increasing the risk of yellowing, according to Joshua Tree Experts.

The Royal Horticultural Society (RHS) also recommends letting the grass grow a little longer in summer. 

In its lawn care advice, the RHS explains: “During hot, dry periods, raising the height of cut helps to keep lawns green.” 

Cutting too short allows the sun to dry out the soil and damage the roots.

Other tips include watering deeply but not too frequently, avoiding cutting wet grass, and mowing during the cooler parts of the day, early morning or evening.

More lawn care advice can be found here.