Can British gardens survive climate chaos?
From summer heatwaves to winter downpours, Britain’s climate is becoming more extreme and unpredictable.
What does it all mean for our very British obsession with gardening?
Experts at Cambridge University Botanic Garden are busy working out which plants are most likely to survive.
Sally Petitt, Head of Horticulture at Cambridge University Botanic Garden, recalls winters so bitterly cold that she couldn’t do any work. Having dedicated nearly 40 years to the Garden, she’s witnessed first-hand the shifts in local climate. “Some winters we couldn’t even go out and rake leaves because they were all frozen solid. That’s unheard of now,” she says.
Sally Petitt, Head of Horticulture at Cambridge University Botanic Garden
Sally Petitt, Head of Horticulture at Cambridge University Botanic Garden
Repeated heatwaves and lack of rain this summer have caused gardeners across the UK to struggle in other ways, whether trying to maintain a decent lawn, get new plants established or keep the prize dahlias alive. Climate predictions for the UK anticipate more periods of extreme heat, frequent drought, and more extreme rainfalls - although whether these will be in summer or winter is unclear.
“We don’t know exactly how our climate will change in future,” says Margeaux Apple, Assistant Curator of Living Collections at Cambridge University Botanic Garden. “Different models predict the UK climate will become more Mediterranean, or more like north-west France or northern Greece."
"What we do know is that a lot of the world is going to experience novel climate conditions that aren’t happening anywhere right now.”
Margeaux Apple, Assistant Curator of Living Collections at Cambridge University Botanic Garden
Margeaux Apple, Assistant Curator of Living Collections at Cambridge University Botanic Garden
The challenge, then, is predicting which plants will be most vulnerable and which more resilient to the changes that lie ahead, something the team at Cambridge University Botanic Garden has long been considering.
Know the site
“Throughout the history of the Botanic Garden there's always been a level of uncertainty about whether what we're growing will survive in the future,” says Petitt, adding:
"Plants have been grown outside of their known ranges here for centuries."
Today, the team uses scientific modelling to help work out what to grow. They compare information on two key factors: the climate range any given species can survive in naturally - particularly the temperatures and rainfall levels it can tolerate, and the climate range in the Garden. They’re looking for mismatches with today’s climate, and with climate predictions for the future.
They’re also trying to understand how adaptable different plants might be to changes in climate - which isn’t easy. There’s variation between individuals, and this is affected by the soil they’re grown in. Across the 40 acres of the Botanic Garden there are varying microclimates, soils, and topography - and understanding all of this is vital.
Change the mindset
Predicting which plants will be most resilient in an unknown future is a tough job. But through ongoing experimentation at the Garden there are many ideas that anyone with a garden in Britain could try.
The drought-tolerant ‘Dry Garden’ was designed for the hot, dry weather that’s causing so many of our garden plants to struggle today. It has never been watered since being planted in 1990 - the only water it gets is from rain. Despite this it’s a riot of colour, with plants including catmint and California poppy buzzing with insects.
The Dry Garden is never watered and is drought-tolerant
The Dry Garden is never watered and is drought-tolerant
“Plants in the Dry Garden have leaves that are leathery, glossy, small or hairy, all of which are adaptations to help mitigate the effects of heat and UV light."
“We also use bulbs like daffodils, which flower early and are then dormant when the weather is most extreme,” says Petitt.
The ‘Dry Meadow’ is similarly drought-tolerant but with a more natural style, and includes species from prairies and grassy plains across the world. Before sowing the seed-mix, gardeners cleared the top layer of soil and replaced it with free-draining sand. The plants, selected to suit Cambridge’s climate, include cowslips and oregano alongside South African Berkheya ‘Silver Spikes’ and Missouri evening primrose.
The drought-tolerant Dry Meadow has species from prairies and grassy plains.
The drought-tolerant Dry Meadow has species from prairies and grassy plains.
“The traditional herbaceous border - which is high-maintenance and needs a lot of watering - is becoming outmoded."
“A better way of growing in future will be to use plant mixes that are better aligned to the specific conditions of your garden,” says Petitt.
She adds: “We need to try and adapt away from the mindset that a British garden must have a traditional lawn, and grow meadows or alternative grass species that do better in drought conditions. That’s going to be big shift for many UK gardeners.”
Manage the water
Water is a scarce resource, and with the constant threat of summer hosepipe bans it’s important to use it wisely. A certain level of watering can’t be avoided at a world-class Botanic Garden with a remit to grow plants from all over the world. But even here, the team is reviewing its approach in response to increasing local demand for water - particularly for housing development - which could affect the aquifer supplying the Garden’s borehole.
Rainwater collection and a borehole provide water to keep the Botanic Garden's collections alive.
Rainwater collection and a borehole provide water to keep the Botanic Garden's collections alive.
“We already collect rainwater from our glasshouses into underground tanks, and we're now exploring how we can expand this to harvest water from many of the other buildings across the Garden,” says Petitt.
While frequent droughts are now common in Cambridge - one of the driest regions of Western Europe – winters can be very wet, making good drainage an important feature of garden design.
“We’re trying to better understand the water-holding capacity of our soils, to inform where we plant different species across the site,” says Apple.
She adds: “Studying the topography - the rises and dips in the landscape - can tell us where water is likely to collect. If extreme wet periods become more frequent, we may need to adapt our planting based on the topography, catering to plants that like their feet wet or plants that will rot in too much moisture.”
Plant the right trees
Considered placement of trees and hedges can create shade to keep plants, and people, cool in hot weather. But unlike plants, trees are very difficult to water effectively. While species like oak have deep roots to tap into the groundwater, others like conifers seem particularly vulnerable to heat.
The Botanic Garden’s Phenology Project, run with the help of a team of volunteers, is tracking the effects of climate change on over 90 trees and woody plants across the site. The project started in 2020, and year-to-year differences in the timing of leaf loss have already been recorded: sycamores, for example, are losing leaves earlier, while alders are keeping theirs later into the autumn.
“We won’t really be able to interpret the data from the Phenology Project until it’s been running for a couple of decades,” says Apple, “but we’ve noticed that several trees have had a mast year recently - when they produce huge crops of fruit. This can be an indication that they’re stressed: they’re trying to produce lots of new trees to ensure the species survives.”
“We’ve also noticed a lot of our tree canopies are thinning over the years. The trees don’t put out as many leaves because they’re stressed by the hot weather.”
“Repeated exposure to stress, for example a drought in summer then a sub-10oC week in winter, can challenge even the most hardy trees,” says Apple.
Stress makes trees more susceptible to pests and diseases, with the added challenge that climate change is enabling these to spread into the UK from other parts of the world. The bacterial disease Xylella fastidiosa, for example, is a serious threat to olive trees, and in response the UK has put strict regulations on their import.
Keep experimenting
With over 8,000 species from all over the world, many plants and trees currently thriving in the Botanic Garden have evolved in climates quite different to that in Cambridge.
“The beauty of horticulture is that you’re constantly seeing what limits you can push, and what microclimates you can use to grow species from other parts of the world,” says Apple.
While new species are still being brought into the Garden through overseas collecting expeditions, some earlier introductions like the Himalayan conifers are struggling to survive. It’s a big experiment - and sometimes the extreme weather in Cambridge leads to failures. But with science and experience on their side, the team’s aim is to make the Garden as resilient as possible to future climate chaos.
“We’re much better informed now than when the Botanic Garden was established in 1846, so we should be in a stronger position to select plants with a good chance of survival,” says Petitt.
She adds: “The Garden is an ever-evolving landscape. If it had never changed, it would have been a pretty boring forty years for me!”
The British garden as we know it is changing, and there are many things we can learn from this expert team.
Five tips for a more climate-resilient UK garden
- Know your garden. Be prepared to experiment, and make a note of which plants thrive or struggle in the specific conditions of your own garden to guide future planting.
- Consider losing the lawn and growing a meadow instead. Use the Botanic Garden’s Dry Meadow Plant List for inspiration.
- Plants with leaves that are leathery, glossy, small or hairy have evolved to withstand extreme heat and long dry periods. Use the Botanic Garden’s Dry Garden Plant List for ideas.
- Mulching with gravel helps the soil stay cool and retain moisture, to prevent plant roots drying out.
- Water wisely. Encourage your plants to be more drought tolerant by watering them thoroughly but only when they really need it. Regular, light watering can encourage roots to grow near the soil surface, rather than deep down searching for moisture, which makes them more prone to drying out.
Cambridge University Botanic Garden is redeveloping its Station Road entrance. Alongside new buildings, new landscaping - designed to highlight the Garden’s work to respond to climate change - will welcome visitors from early 2026.
The Garden is always looking for donors and partners to help support its activities. To find out more, visit the website or email development@botanic.cam.ac.uk
Published 4 September 2025
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