Inside Kew’s new ‘Carbon Garden’ — built for climate change
To gardeners watching their old favourites wilt in the summer heat, it’s obvious that some plants are struggling during hot summer days, but it’s not so obvious what to do about it.
Luckily, the scientists at Royal Botanic Gardens in Kew have some advice to offer.
It comes in the form of a “carbon garden”, filled with plants chosen to survive the hotter, stormier, more drought-prone climate that scientists predict we will experience in coming decades.
Many of its 6,500 new plants and 35 trees are drawn from the Mediterranean, South Africa and California, while others are native species that are coping well with hotter temperatures.
“A lot of this is experimental” said Richard Wilford, head of garden design at Kew Gardens. “We’ll see what survives and what doesn’t.
“By 2050, we think we’ll have the climate of Barcelona in London. That may sound lovely, but actually it means there are a lot of things to deal with — more droughts, more heatwaves, more storms. What we can do in our garden is try and plant things that will cope with that heat and drought better.”
Richard Wilford at the carbon garden
SEBASTIAN KETTLEY/RBG KEW
INES STUART-DAVIDSON/RBG KEW
The “dry garden” is given over to largely Mediterranean species that can cope well with prolonged dry periods and intense downpours — both of which Britain can expect more of as the climate warms.
Red and yellow coneflowers and interspersed with lavender, rosemary and Mediterranean spurge have been chosen here. This area’s sandy soil filters water quickly, preventing the roots from rotting during periods of heavy rainfall.
“We’ve watered the plants to get them going” said Justin Moat, senior research leader at the gardens, “but we can’t afford to have species that need continual watering. It would be expensive for us and bad for the environment.”
Further in is a native wildflower meadow with yarrow, cowslip and ribwort plantain. “Meadow species are actually pretty good at dealing with changing conditions,” Moat said. “Compared to trees they can adapt quite quickly, because they have a relatively fast turnover, so the most genetically adapted plants can come through.
“Trees on the other hand are sitting there for two hundred years, if not a thousand years. They’re going to be in a different environment from when they started. We know British oaks are doing really badly at the moment, with the increasing number of droughts.”
The trees in the garden, such as oriental hornbeam, Japanese elm and Persian ironwood, have been chosen because they can deal both with hot, dry summers and soggy winters.
Justin Moat
SEBASTIAN KETTLEY/RBG KEW
Another section of the garden shows how to deal with intense downpours when they arrive. A long, shallow depression called a swale wends its way through the garden. In periods of heavy rain, the swale will collect water and stop it rushing into the Thames. “If you have parts of your garden that are flooding, then rather than trying to manipulate it, maybe you could turn it into a swale and enjoy the plants that grow in there,” Moat said.
While the garden is divided into different ecosystems, Moat believes the most resilient gardens will be those that give space to a wide range of native and non-native species. “If your garden is a monoculture with one ecosystem, then some years it may not survive well, but if you bring diversity into it then, OK, one species may do poorly this year but another species may do really well. So that mixture is actually going to be pretty important, and it’s great for wildlife.
“We need to get used to a bit more messiness in our gardens. We imagine our gardens as these perfect lawns and beds, but realistically we’re not going to be able to continue doing that. We need to move away from that very English idea of perfection, and make things a bit more diverse.”
What plants will do well in the changing climate?
When you’re choosing plants that will flourish in a hotter climate, Wilford’s main advice is to choose things that can cope without much watering. “It’s worth looking at things like rosemary and sage. Bearded irises can cope really well with a dry spell.
“Spring-flowering bulbs will give you a lot of colour in spring, but then they can survive the summer without any water at all because that’s when they’re dormant.”
If your garden is shady, however, you may not have to think so much about bringing in new plants to deal with dry summers.
Choosing the right tree for the changing climate is a tougher task because over the course of its lifetime it will have to deal with a great deal of change. Native field maples have been found to cope well with the changing climate, as have sweet chestnuts.
If you’re in an area prone to heavy rainfall, and do fancy digging a swale, then Wilford recommends planting it with red cardinals. “They’re not aquatic, but they don’t mind getting their feet wet.”