One of the container gardens at the 2026 Chelsea Flower Show is drawing attention to a growing flood-risk problem that many UK gardeners overlook.
Garden design and flood risk
Research from Flood Re shows that 82% of garden owners believe their plot can handle heavy rain, yet almost one-third do not realize that paving and other hard surfaces raise flood risk, and only 3% factor flood danger into garden plans.
Hard surfaces prevent rain from soaking into soil. The study notes that just 5mm of rain on a 20-square-metre garden can generate about 100 litres of runoff – roughly the volume of a full bathtub.
When runoff from gardens meets water spilling off roofs and gutters, the combined flow can overwhelm local drains, especially on streets lined with paved yards.
Climate change is increasing the frequency of intense storms, making the runoff from hard-scaped gardens a more pressing concern for residential areas.
The average cost of flood repair for homeowners now exceeds £30,000, according to the insurer, highlighting the financial stakes of better garden design.
“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.”
He added that the spread of paved areas, a process described as ‘urban creep,’ forces more water straight into sewers, while slowing water at its source in gardens can be a simple, effective mitigation.
Contain the Rain garden showcases solutions
The Flood Re: Contain the Rain garden, part of the show’s balcony and container displays, demonstrates how planting and permeable materials can both look attractive and manage water.
The garden features remodelled containers that collect drained surface water; a button releases the stored water to moisten topsoil during dry periods, improving retention.
“Our garden provides a blueprint for everyday people to help flood-proof their gardens,” said Kelly Oster-Coyle, head of corporate affairs for Flood Re, “from including a high density of trees and plants to help absorb surface water, to ensuring damp topsoil to maximise retention and avoid run off.
Plants such as Astilbe ‘Deutschland’ and Astilbe ‘Dark Side of the Moon’ are highlighted, proving that aesthetic choices can also serve practical water-management purposes.
Practical steps for homeowners
Visitors can view the Contain the Rain garden at the Royal Horticultural Society exhibition, and a guide to the show’s balcony and container gardens is available online for those seeking detailed design ideas.
