WIREDGOV

In late February 2019, an historic climate event occurred. A flow of very warm southerly air (in conjunction with an area of high pressure) resulted in the first recorded occurrence of temperatures in excess of 20 °C during a UK winter season, reaching 21.2 °C at Kew Gardens.

This week delegates of the PlantNetwork charity’s annual conference will be gathering at Abbotsbury Subtropical Gardens to discuss the issues posed by climate change and how these will affect the nation’s gardens and designed landscapes.

The February warm spell created several issues for gardeners:

• many garden plants emerged rapidly from their dormancy (only to be damaged by the frosts in April);
• lawns required their first and second cuts much earlier than normal;
• many gardeners needed to water their gardens.

Janet Manning, Water Management Specialist at the Royal Horticultural Society, said:

“Twitter was scattered with tweets from gardeners who felt the need to water their gardens for the first time ever in February,”

Taro (Colocasia esculenta) – a tropical root vegetable from southern Asia – might become more widespread across southern Britain in future: it already grows well at Abbotsbury Subtropical Gardens cared for by curator Stephen Griffith (pictured).

Gardens have to endure drought, heavy rainfall and extremes of temperature. The types of plants grown in gardens and how gardens are designed and managed will need to change to take into account higher temperatures and changing rainfall patterns. Key to all of this is translating the current climate projections to gardens around the country.

John Edmiston, of the nursery Tropical Britain, considers the types of plants we might be growing in a hotter, drier climate. He said: “Climate change will have a massive effect on British horticulture. Gardens will need to be more resilient to drought. The dominant style in British garden design has for many years focused on herbaceous perennials soaking up large quantities of water. As we move into a hotter drier future, many public gardens and garden designers will use more plants adapted to dry conditions, combining hardy desert species with drought-resistant perennials to create a new style. Fifty years from now, British gardens will look quite different.”

Dr Mark McCarthy is the head of the Met Office’s National Climate Information Centre. He said: “The UK climate is warming, increasing the likelihood of events such as those seen in February and last summer’s heatwave. The latest set of UK climate projections (UKCP18) show that extreme hot summers like 2018 or 1976, could be more frequent by the 2050s, and that our winters are very likely to be milder and wetter.”

Invasive potential

Introducing plants into gardens from around the world is not risk free. New pests and diseases have the potential to spread into the UK on a variety of plant material and in soils, particularly as the UK climate becomes more amenable to their survival. Tomos Jones, a PhD student at the University of Reading, has studied the invasive potential of many ornamental plants. Tomos said: “Climate change could allow more ornamentals to become invasive, as conditions become more suitable. Gardeners have an important role to play in preventing plant invasions, in their choice of plants to grow and in disposing of potentially invasive plants responsibly. Gardeners are on the ‘front line’ in identifying plants in their gardens showing ‘invasive characteristics.”

There are design challenges too. Heritage gardens often use a narrower range of plants than we now have available, but a changing climate might mean that these gardens and landscapes will need to find plants better able to survive rather than being true to the period of the garden. Water and soil management are crucial factors in horticulture and are vital in a changing climate.

Everyone can make a difference. But those small changes can really add up to a significant impact. As Janet Manning, added: “If the 27 million gardeners in the UK could save just one watering can full of mains tap water this summer, we would have saved enough water to supply Bristol, Leeds and Sheffield for a whole day, that’s significant and achievable.”

Simon Toomer, PlantNetwork Chair, said: “Now is the time for horticulture – an industry worth £24bn to the UK economy – to step forward and be part of the solution:, planting a tree is still one of the quickest, simplest and cheapest ways to remove carbon from the atmosphere.”

• PlantNetwork is a charity supporting gardens, arboreta and other plant collections through training, networking and information exchange between gardens. This year’s major topic at the annual conference is “Climate Change and Gardens”, professional gardeners from across Britain and Ireland will discuss how the sector can be better prepared for a changing climate.