Gardeners are being urged to place a 2p coin in birdbaths this summer to keep water clean and safe for visiting birds and wildlife. The copper content in pre-1982 pennies releases trace amounts of copper ions that naturally inhibit algae and bacterial growth, according to experts at Gardening Know How.
How Copper Coins Work
Copper acts as a natural biocide, interfering with the biological processes that algae and other microorganisms rely on. As the coin sits at the bottom of the birdbath, it gradually leaches copper into the water, creating an environment that discourages green algae and slime. Rocky Trifari, bird enthusiast and owner of The Rocky Safari, explains: "Copper is a natural biocide with properties that interfere with the biological processes algae and other microorganisms rely on. When copper ions leach into the water, they promote an environment that discourages the growth of green algae, one of the main causes of that slimy, dirty water found in birdbaths."
Choosing the Right Coin
Not all coins are suitable. Only one or two-penny pieces dated before 1982 contain sufficient copper to trigger the beneficial chemical reaction. Coins minted after 1982 are made mostly of zinc with a thin copper plating and will not work as effectively. Gardeners should inspect coins for rust or deterioration before use and clean them using natural methods, avoiding harsh chemicals.
Expert Advice on Maintenance
Chris Bonnett, founder of GardeningExpress.co.uk, emphasises that birds need fresh water year-round: "It's easy to assume that since it's cold, birds don't need or want a fresh water supply but this isn't the case at all. Just like us, birds need regular access to a clean and fresh water source so it's important to keep filling bird baths." He adds: "If you find your birdbath quickly attracts algae you can actually place a 2p coin at the bottom once it's cleaned to help slow down the growth of it. This means you might be able to go a bit longer before having to give it another clean."
Safety Considerations
While copper is effective, excessive exposure can be harmful to smaller bird species. Experts recommend using only one or two coins and never relying solely on this method. Regular cleaning with a rinse and scrub remains essential, especially in summer when warmer temperatures accelerate stagnation and contamination. The coin trick is an additional measure, not a replacement for proper hygiene.
Summer Importance
With Britain experiencing successive heatwaves, birdbaths become vital water sources for thirsty wildlife. A clean birdbath helps prevent the spread of diseases among garden birds. By adding a copper 2p coin, gardeners can maintain fresher water for longer periods, making their gardens a safe haven for birds throughout the summer months.
