View the map

Back

Clear Lake

Clear Lake is a man-made lake collecting rainwater for irrigating the garden, with gently sloping sides providing the perfect habitat for Wisley's wildlife

Looking its best in...

  • Early spring Cherry blossom on the island
  • Early summer wonderful flowering meadows surrounding the lake
  • Autumn superb autumn colour from the trees
  • Late winter enjoy the reflections of giant redwoods in the lake, most of them over 100 years old

Giant water butt

An exciting new project has been officially opened at RHS Garden Wisley. Affectionately described as a giant water butt, Clear Lake is a man-made lake created on the former trials fields below Battleston Hill and holds the equivalent of 42,000 domestic water butts. 

Funded by Marit Mohn, a long-standing RHS member and RHS Fellow, the lake features a giant fountain which aids water quality, through aeration, and helps reduce the sound of the nearby road.  Gently sloping sides, provide the perfect habitat for a wide range of creatures and plants. With a total capacity of 9 million litres, the water level will never be allowed to drop below 3 metres, which is approximately 3 million litres of water, ensuring the wildlife is sustained at all times.

Wonder of water

As climate change continues to surprise us with ever-changing weather, collecting and using water is vital to the long-term health of our gardens. Situated in the basin behind RHS Hilltop, Clear Lake collects rainwater runoff from the buildings, enough to irrigate the ten acre woodland garden at Battleston Hill during dry spells, as well as providing a diverse wildlife habitat and a beautiful space for visitors to enjoy.

Alongside the glasshouse lake, the borehole in The Pinetum and various underground water tanks, the lake forms an important part of the RHS Sustainability Strategy to be water neutral by 2030.

Be water wise

  • Use a watering can instead of a hosepipe
  • Place drip trays under pots in summer
  • Add mulch around plants to keep moisture in the soil
  • Use a water butt to collect and store rainwater

Opening celebration

A grand opening was held in May 2023, celebrating this incredible transformation. Officially opened by RHS member Marit Mohn and her granddaughters Clara and Aurelia, whose names are carved into the wood on the two stunning oak-framed pavilions constructed by Surrey Oak Barns.  Clear Lake brings beauty and function together.


 

Powerful plants

The two pavilions are surrounded by a developing wildflower meadow, boosting the site's biodiversity.  Against the backdrop of existing mature conifers, newly planted trees - Carya (hickory), Acer rubrum (red maple) and Metasequoia - inject vibrant autumn colour but have also been chosen for their climate resilience. Giant redwoods tower over the area providing a powerful background to this tranquil setting.

"With hotter, drier summers and extreme
weather events, harvesting rainwater
like this is a sensible choice, and it
can be done by anyone, on any scale.
It’s a landscape for now and the future."

Matthew Pottage, Curator

"With hotter, drier summers and extreme
weather events, harvesting rainwater
like this is a sensible choice, and it
can be done by anyone, on any scale.
It’s a landscape for now and the future."

Matthew Pottage, Curator

Plants in this section

You may also be interested in...

Wildlife gardening in a changing climate

Wildlife gardening in a changing climate »

Water: collecting, storing and re-using

Water: collecting, storing and re-using »

RHS Gardening in a Changing Climate Report

RHS Gardening in a Changing Climate Report »

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.