Water fern

This popular pond plant, originally native only to North and Central America, is also known as Fairy Fern. There’s certainly nothing delicate about this floating nuisance though, which forms dense mats on the water’s surface, which pose a hazard by appearing solid.

Water fern surrounding boat Water fern, copyright GBNNS

Able to withstand British winters and invade a region very rapidly, this innocent sounding plant has dominated many waterways in its time. Water fern spreads like a sponge across the water and can double in area within a few days.

This reduces light beneath the surface and shades out other native plants, as well as causing de-oxygenation leading to the death of fish.

The plant is entirely free-floating and so able to grow in any depths, but the water must be still or slow moving for it to properly thrive. In pioneering science, a ‘biocontrol’ has been developed.

This is a tiny insect from the plant’s natural range, which actually eats water fern. It is a very effective control and can bring this weed under control within a few weeks. We pay a company to supply the insects for us as and when we need them.

Last date edited: 15 March 2018