A small container garden at the RHS Chelsea Flower Show highlights an important message about the risk of flooding in UK gardens. According to new research by Flood Re, millions of homeowners in the UK could be ‘sleepwalking into a flooding crisis’.
Flood Re says 82% of garden owners in the UK think their plot would cope with heavy rainfall, but almost one in three don’t realise paving and other hard surfaces can boost the risk of flooding.
Gardens with a high proportion of planting and permeable surfaces allow rainwater to soak into the ground. Spaces with paving and other hard materials increase the amount of surface runoff, putting extra pressure on drains.
Just 5mm of rain in a 20-square-metre garden can create 100 litres of runoff, the equivalent of a full bathtub of water.
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When combined with rainwater runoff from roofs and gutters, and multiplied across a residential street, gardens with a large proportion of paving boost the risk of flooding. Climate change brings increasingly unpredictable weather events, making this issue more pressing.
“Intense rainfall alone doesn’t cause flooding – it’s all about what happens to rain when it hits the ground,” said Dr Peter Melville-Shreeve, associate professor at the University of Exeter. “Hard surfaces like our driveways and rooftops disrupt the natural hydrological cycle and stop water soaking in.
The Flood Re: Contain the Rain garden – one of the show’s balcony and container gardens – showcases how garden design can hold and slow rainfall.
“This garden is about showing that you don’t have to choose between beauty and resilience,” said the designer John Howlett. “By using planting, permeable materials and thoughtful design, you can create a space that looks great but also works much harder when it rains.
The garden showcases several clever features, including remodelled containers underneath to store drained surface water. At the push of a button, it is then released to dampen topsoil to help with water retention during warmer months.
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“Our garden provides a blueprint for everyday people to help flood-proof their gardens,” said Kelly Oster-Coyle, Flood Re’s head of corporate affairs. The team focuses on including a high density of trees and plants to help absorb surface water. They also ensure damp topsoil to maximise retention and avoid run off.
It’s worth considering the broader implications of garden design on flood risk, as the way we manage rainwater in our gardens can have a significant impact on the surrounding environment and community.
Plants such as Astilbe ‘Deutschland’ and Astilbe ‘Dark Side of the Moon’ feature heavily in the garden, highlighting that gardens can be both beautiful and practical.
Implementing these strategies helps reduce the risk of flooding.
