Leaving your garden lights on may feel like an extra layer of security to your home, but it could actually have a serious impact on outdoor wildlife, experts have warned.
From birds to bats, this mistake could put a wide range of species at risk without you even realising, which is why it’s important to turn lights off when they’re not in use.
Below, you’ll find out why this common error is such a bad idea, and the safer garden lighting alternatives you can switch to instead.
Why is it a bad idea to leave your garden lights on overnight?
Whether you leave your garden lights on for added security and to keep your home safe from burglars or simply forget to switch them off, keeping them on overnight can be bad news for wildlife in your garden.
"Some species of bats avoid light areas altogether, while for other animals such as common frogs, artificial light can lure them in. We’ve probably all seen moths flying around a street or security light – becoming exhausted and put at higher risk of predation," says Helen Bostock, Senior Wildlife Specialist at RHS.
She explains that while animals that are most active during dusk, dawn or during the night are obviously most impacted, new evidence has found that day-active wildlife can also be affected.
"Robins, for instance, will keep hunting and singing in lit-up streets, using up vital energy. Birds that prefer to start their migration under cover of dark can become disorientated with our brightly lit cities," she says.
What's more, a study published in the Journal of Biological Conservation found that light pollution is a driver of insect declines, as it affects their movement, foraging, reproduction, and predation.
“Homes must be designed to be wildlife-friendly, from lighting to garden landscaping, to help nature thrive alongside people. Just like turning off the tap when you brush your teeth, if everyone turns a garden light off at night, we'll be making a difference for wildlife," adds Richard Benwell, Chief Executive of Wildlife and Countryside Link.
Helen is the Senior Wildlife Specialist, working with the Plant Health team to provide wildlife gardening expertise and lead on developing and delivering biodiversity positive targets for the RHS Science Strategy and Sustainability Strategy
Richard Benwell is chief executive of Wildlife & Countryside Link. He is also a board member of the Broadway Initiative and UK Youth for Nature and Chair of Oxfordshire's Local Nature Partnership.
Which garden lights are the worst for wildlife?
LED lights – particularly those with cooler colour temperatures – are one of the worst culprits of light pollution. If possible, Helen Bostock recommends switching them to a low-intensity, warm white bulb – aim for 2700 Kelvin or lower.
Where to buy wildlife-friendly garden lighting
This stylish outdoor light features a built-in motion sensor to ensure it never switches on unnecessarily.
These warm white bulbs have a colour temperature of 2,700K and a 38-degree beam angle that's perfect for accent features.
How can I reduce light pollution in my garden?
To reduce light pollution in your garden and minimise the impact on wildlife, Helen Bostock recommends the following steps:
1. Keep your garden dark: If possible, leave areas of your garden completely dark and include a safe passage across the space.
2. Keep light to a minimum: While you may need to illuminate some areas of your home, such as the front door or security systems, you can reduce the impact by using motion sensors for short periods.
3. Angle your lighting: If possible, angle your lighting downwards or fit a cowl over the top to deflect it.
4. Choose low-intensity solar lights: These will have less impact than harsh, bright LEDs (and are cheaper to run as a bonus).
5. Avoid garden pond lighting: This will help pond life remain undisturbed.
6. Draw your curtains: Don’t forget about the lighting inside your home too. Keep blinds and curtains closed after dark, including on patio doors.
While it might be unrealistic to keep your garden in total darkness every evening, there are a number of ways to reduce your impact – from switching to a warm-colour-temperature bulb to opting for a motion-sensor holder.
For more expert advice on this topic, read our guide on garden lighting laws or take inspiration from these incredible eco homes.
