Gardens for the future: UK landscapers switch to drought-resistant planting as climate changes

The Guardian

3 days ago

Rare succulents, palm and monkey puzzle trees, beaked yucca and oriental hornbeams are just some of the new features in the historic gardens of England, as head gardeners get to grips with the changing climate this summer.
In the Grade I-listed landscape at Sheffield Park and Garden, an historic English landscape in Sussex, designed in the 18th century by Capability Brown and Humphry Repton and famed for its rhododendrons and azaleas, the National Trust has planted a 'more resilient' garden – featuring drought-resistant flowers and trees from South America, Australasia and the Mediterranean.
Where once there was just a grassy clearing, there is now a Garden for the Future full of purple and blue salvia, yellow aloes, palm and monkey puzzle trees, rare beeches and other exotic and subalpine plants.
Historic English gardens are being forced by the UK's changing climate to increase the resilience and diversity of their living collections and plant displays, and the results are fascinating. Next week, for example, visitors to the Royal Botanic Gardens in Kew, London, will get a chance to see Montpellier maples, beaked yucca, rare succulents and oriental hornbeams when the Carbon Garden opens there on 25 July.
The design also invites visitors to journey from a planting of cool purple and blue herbaceous perennials towards bright red crocosmia and achillea, to illustrate the dramatic rise in global temperatures over time, inspired by climate stripes.
It includes a dry garden and a rain garden, as well as wildflower meadows, grasslands and carefully selected resilient trees, such as Mediterranean cypresses and Persian ironwood.
'We're trying to be more positive in our thinking about how we adapt gardens and habitats to the threat of climate change and the carbon cycle, and highlight some of the solutions – or at least the mitigations – that we can make to manage some of the impacts of climate change,' said Simon Toomer, curator of living collections at Kew.
Strategies include growing more diverse and drought-resistant plants, prioritising water capture and biodiversity and using shade planting to shelter Kew's most vulnerable flora and fauna. 'The Carbon Garden will give us an opportunity to do that at a concentrated level,' Toomer said.
Further south, Kew is already reaping the benefits of climate-resistant planting. In Wakehurst, formerly the grounds of an Elizabethan mansion and now home to Kew's millennium seed bank, an 'American prairie' of rare grasses, Black-eyed Susans and Mountain Mint is thriving this summer.
Planted with hundreds of thousands of wild prairie seeds from North America in 2020 as an experiment, horticulturists say as many as 85 different species – well over 40,000 plants – are now successfully established in the Sussex landscape, boosting biodiversity in the area.
Earlier this year, gardeners even discovered a prairie plantain – which has thick, rubbery leaves, is adapted to living in very dry conditions and can grow up to five feet tall – flowering for the first time.
Susan Raikes, director of Wakehurst, said prairie plants have been 'very happy' in the 30-degree heat this summer. 'The root systems of most of them extend a meter underground, so they tap into the water table below, which makes them really resilient to the kind of hot summers we're experiencing now. Their deep roots also mean they capture and store a lot of carbon in the soil.'
She hopes the beauty of the flowers in the summer will also inspire visitors to plant prairie species in their own gardens. 'Some are fabulous for pollinators – they are the sort of plants we're going to need to plant in the future in this country to protect our pollinator population.'
However, she warns that prairies die back in winter. 'It isn't a landscape that looks beautiful all year round.'
In the future, historic gardens may have to separate their planting into winter gardens which can flourish in wet, cold and windy conditions and summer gardens which can survive hot dry conditions, she said. 'Plants are adapting, but we're going to have to adapt as well. What we can expect from our gardens and landscapes will have to be different in the future.'
A few miles away, award-winning garden designer Joe Perkins used raised, mounded beds to address this problem when he created the Garden for the Future for the National Trust this summer: the first major change to Sheffield Park and Garden since the charity started looking after it in 1954. 'It is predominantly heavy clay soil throughout the site and that poses real problems for the existing trees because it dries up and cracks in the summer, which splits apart their root system,' Perkins said. 'And there's no point planting very drought-tolerant plants in heavy clay, because they're going to die in the winter, when the soil holds a lot of water.'
Since plants that can cope with drought 'don't like sitting with their feet in the water during the winter' a lot of the plants in the new garden are in raised planting beds, he explained: 'The soil we've put in those beds is a mixture of recycled, finely crushed brick, soil and compost, to make it very free-draining.'
Historic English gardens should not be viewed as set in stone: they are a living part of our heritage and must be allowed to experiment and evolve to address the climate emergency, he argued. 'They've got to be progressive – and places like Sheffield Park were always progressive. It was always a garden of exotic plants, and it needs to be able to adapt to the conditions we are facing.'
Newly published scientific research into the trees that have the best chance of withstanding changes to the climate at Kew in the future has been used to inform the 35 new trees that have been planted in the Carbon Garden. Kew's scientists also used cutting-edge light detection and ranging (LiDAR) technology to figure out which tree species are the best at capturing and storing carbon, with visitors invited to look through binoculars in the garden and view a 3D LiDAR model of a nearby tree.
Toomer said: 'There's a high likelihood that up to half of the trees at Kew will be suffering and not thriving towards the end of this century,. So we're responding to that by planting different kinds of trees.'
Perkins thinks it's vital that historic gardens, working with scientists, are open to such changes. 'We need to experiment, to move our gardens forward, to be more resilient for the future,' he said. 'If we don't push boundaries, we won't learn – and we need to learn fast.'
BOX Which plants work for gardens in a drought
Parry's agave, a flowering succulent perennial native to Mexico and Arizona.
Beaked yucca, a tree-like shrub native to Texas and Mexico.
Euphorbia niciciana, a semi-evergreen perennial with narrow, lance-shaped, widespreading, glaucous green leaves and clusters of yellowish to lime-green flowers.
Verbena bonariensis, a herbaceous perennial that can grow to 2m tall. It thrives alongside other drought-resistant plants such as lavender and has clusters of lilac nectar-rich flowers that attract pollinators, while birds will eat its seeds.
Santolina - also known as cotton lavender - has silvery, hairy leaves that reflect the sun's rays, enabling it to survive high temperatures.
Deciduous agapanthus, which are native to South Africa, have delicate flowers in shades of blue, violet and white.
Aloiampelos striatula, a bright South African succulent, can store large amounts of water in the leaves.
Eryngium, commonly known as sea holly, is a dramatic, spiky and drought-tolerant plant with metallic blue, purple or silver flowers that are highly attractive to bees, butterflies and ladybirds.
Sesleria autumnalis – a hardy, long-lived grass which grows white flowers in summer and has golden green autumn foliage.
Salvia, such as the dark purple 'Nachtvlinder' from Mexico, are colourful, hardy and attractive to pollinators.
Hesperantha, native to South Africa, has crimson flag lily flowers that bloom in late summer into autumn, providing colour to fading borders and nectar for late flying pollinators.
Compiled with help from Kew Gardens and the National Trust.