Turning Waste into Blooms: RHS Trials Compost Toilets
For over two centuries, the Royal Horticultural Society (RHS) has championed the use of compost and manure in their gardens. Now, they're taking sustainable practices a step further by introducing their first-ever composting toilet at RHS Garden Wisley in Surrey.
This innovative addition is part of the new Greener Skills Garden, an off-grid space designed to educate horticulture students and the public about sustainable gardening and mitigating the effects of climate change on plants. The garden will showcase environmentally friendly ways to manage human waste, among other sustainable practices.
Lewis George, an RHS horticultural engagement officer overseeing education in the garden, explained the composting process. "Material" deposited in the toilet will spend 18 months in a large-capacity container, followed by six months in a traditional compost pile. The resulting compost, or "humanure," will then be used as a soil improver on ornamental, non-edible plants within the Greener Skills Garden.
Initially, George will be the sole gardener responsible for handling the humanure, reflecting the RHS's cautious approach in a public garden. "We're going to be extra cautious, because we're a public garden," George stated. However, he anticipates expanding the program in the future. "If we ever get to the point where we're really churning through masses of material, I'll be offering it out to other garden teams.”
George expressed his enthusiasm for the project, highlighting the numerous benefits of composting human waste. "I'm really passionate about it," he said. "It's great recycling and it's a great source of organic material that can feed our soils - but it also saves water and helps prevent sewage spills going out into rivers, which occur because of the capacity problems of our sewage system." He added, "This is one of the ways we can be much more responsible about our waste and get something really beneficial from it. So for me, it's a no-brainer.”
Wisley, established in 1878 as an experimental garden focused on cultivating "difficult plants," now welcomes over one million visitors annually. George believes the composting toilet and the Greener Skills Garden align perfectly with Wisley's history of innovation. "A composting loo and the wider Greener Skills Garden really fits in with that original ethos of experimenting and pushing the boundaries of what we do in horticulture," he commented.
Dr. Chloe Sutcliffe, an RHS sustainability fellow, shared details about another feature of the Greener Skills Garden: Wisley's first rain garden. This garden will feature plants capable of tolerating both waterlogged and dry conditions. The experiment aims to demonstrate how different planting schemes and rainwater storage overflow can effectively manage heavy rainfall within a garden. "We're encouraging visitors to be able to see the journey that water takes through gardens, so that people can start to understand how gardens can be used to slow the flow of water across the landscape," Sutcliffe explained. "That is something we increasingly need to do to try to increase our resilience to heavy rainfall and reduce the risk of flash flooding in the future.”