Research by the wildlife charity, Butterfly Conservation shows that long grass can boost butterfly numbers by up to 93%. Long grass is important for butterflies and moths throughout their lifecycle, with adult butterflies and moths nectaring on wildflowers which pop up in long lawns and several species laying their eggs on grasses. Many caterpillars also rely on long grass throughout the spring and summer months for food.

For this reason, the charity says that it’s important to leave parts of grass to grow long from April to September. They recommend, come September when the lawn is mown not to cut all the grass at once. Leaving 20% uncut all year long provides refuges for overwintering eggs and caterpillars, supporting the next generation of butterflies and moths.

With gardens making up more than 728,000 hectares in Great Britain, the seemingly small step of leaving a patch of grass to grow long in each of these gardens could make a huge difference for butterflies and moths. Last year, Butterfly Conservation declared a national ‘Butterfly Emergency’, with results of the 2024 Big Butterfly Count showing a marked and hugely concerning decline in numbers.

As a sign of commitment to the campaign, over 3400 people have pledged to be a “grower not a mower“, to date.