Friends of Westonbirt Arboretum

Protecting our trees

The problem

The last few years have seen the UK’s trees under attack from at least 32 significant diseases and pests, including the devastating Chalara Ash Dieback. These threats are casting a very dark shadow over Westonbirt Arboretum. Within our vast collection of living specimens, over 100 different species are already classified as threatened and in need of conservation. We’re facing a very real threat – and with ongoing climate change it’s only going to get worse. We need to take steps now to protect our trees before it’s too late.

Chalara ash dieback

What we’re doing

Thanks to generous donations from our supporters we are able to build a Quarantine House in Westonbirt’s Propagation Unit. This specialist facility will drastically boost our biosecurity, allowing us to isolate new plant material, such as seeds and young plants, and regularly check for signs of pests or disease. By checking their health, we can also apply the correct biological controls when required to handle any pests without the use of chemicals and pesticides.

Britain’s natural heritage is characterised by a vast range of trees, shrubs and plants. With changing land use in the UK, little remains of Britain’s native woodland. What we have left is unique, precious and endangered by the threat of non-native pests. The Quarantine House is vital to protect the living tree collection and historic landscape here at Westonbirt. The acquisition of new plants into the living collection at Westonbirt is crucial to the conservation and protection of rare and endangered trees in this botanical garden and will ensure that future generations are able to enjoy the arboretum.

Propagation at Westonbirt Arboretum
Propagation at Westonbirt Arboretum

The majority of new plant material arrives as seed, often collected from the tree’s natural habitat by way of our own authorised foreign seed collecting expeditions or an expedition undertaken by one of our many partner organisations. We have a critical role to play in sharing and exchanging surplus plants and seeds with other partner organisations, often where more plants have been grown than is required by a collection. All new plants and seeds will firstly be screened and scrupulously checked before given approval for planting. This way we can be sure that any new additions to the arboretum will be free from disease, pests and pathogens. Put simply, a Quarantine House will make our arboretum more resilient to disease.

Behind the scenes, the Tree Team monitor Westonbirt’s trees through the routine maintenance and development of our collection; which requires meticulous record keeping across this ever-expanding and changing site. This important scientific research will form part of an international plant sentinel network. We share our findings with our national and international partner organisations, including the worrying first leap of Chalara Ash Dieback to non-ash species hosts within the arboretum. By sharing this knowledge we can better protect trees, woodlands and natural habitats across the world. The new Quarantine House is a much-needed addition to our work and will help us to safeguard the future of our trees.

Propagation area at Westonbirt Arboretum


The Quarantine House will sit within the Propagation Unit on site. The structure itself has many different layers, each with a bespoke role to play.

- An outer poly-tunnel provides essential protection against the elements, a barrier to wind and water shielding an inner structure.

- The inner shade hall will be covered in aphid-proof netting and securely sealed to prevent pests attacking the young plants directly or carrying and transmitting disease to them.

- The external entrance into the inner central compartment and, the internal entrances to the quarantine bays on either side, will have sealable double doors, effectively isolating the compartments from one another.

- Within the central compartment/corridor, there will be a disinfectant trough and mat with footwear dedicated for sole use within the quarantine bays, together with storage for nursery equipment.

- Each bay will have running water with a sink and drainage. The floor of the quarantine bays will be gently sloped to a central drainage point, leading to an underground water collection tank, preventing potentially contaminated water from seeping into the surrounding area.

- The quarantine bays will each have fixed waist-high roll-top benches and a lower bench for differing sized plants.

- Internally, lighting and electrical sockets will be fitted to include a fridge within each bay to help replicate germination conditions for certain tree species. In addition to electric fans positioned to increase air circulation.

Westonbirt's Quarantine House
Westonbirt's Quarantine House


The contractors arrived on site on Monday 22 November and the groundworks have now commenced. The installation of the main structure itself is anticipated to progress quickly and the team have completed a dry run at their workshop. The internal fitting-out of the structure will take place in the New Year with the Quarantine House being fully operational by spring 2022.

Watch the Quarantine House speedbuild video:

Donor Appreciation

Your gift has made a huge difference to our project - thank you.

Banister Charitable Trust

Finnis Scott Foundation

Foxley Road Nurseries

Stanley Smith (UK) Horticultural Trust

N R Aker

Graham Allnatt

Thomas P Ashenden

Jenny A Barnett

Jennifer Best

Sally Bexton

Rob Bick

Joanna Borrett

Janet K Bowers-Broadbent

Sue E Bradley-Jones

Muriel K Brooke

Thomas N Brown

Angela R Buckell

Robin Campbell

Roy F Carey

Peter J Carpenter

Margaret Cheese

Carol Clarke

David Clarke

Deborah H Clogg

Christine M Cole

Jo Cox

Cathelijne Cuellar

Keith D Cuthbert

Jacqueline Dalton

Patricia Davies

Diana P Davies

Brian Dejean

Vivien M Donkersley

Jim Druett

Janet Duffy

Mary Durell

Janice Eades

Nigel J Edwards

James Edwards

Shirley Elder

Andrew Evans

Keith Faraday

Geoffrey Fitch

Alison Flint

Dee Gardner

Alan Garner

Paul Gibson

Susan Grazebrook

Clive Greaves

Neil Grecian

Martin J Green

Arthur J Gregory

Edward Greves

Robert J Harding

Roland L Harley

Evelyn Harlow

Muriel Harrison

Ian J Harvey

Carollyne Haynes

Margaret B Headen

Brian Heath

Rachel C Hemming

John Hobday

Maureen Horscroft

Andrew J Howe

J N Hughes

Alan Hunt

Mark R Ingram

Clive Jefferies

Pamela Kellett

Alan R Kempton

John E Kendall

Jane L Kimpton

Jeffrey Lacey

Michael J Latham

M Leggett

Rosemary Levett

Joan Lilly

Margaret E Lloyd

Jinny J Marshall

Karen H McKeown

Eileen Menzies

Christine Menzies

Susan Middleton

Stephen R Montgomery

D Moray

Allan Peter P Moss

Tim J Mugford

Margaret Muttram

Janet Newby

David Penn

Grace Pownall

Ian Rea

Gillian M Rodger

Lesley Rossiter

Margaret Ruskin

James Scott

Peter Scott

Peter Seaborne

Richard M Shaw

Pippa J Smith

Andrew Smith

Stephen Spooner

Andy Strong

David R Swinson

Sue E Symonds

Barbara Tagholm

Harriet R Tupper

Alan J Turk

Ian Unsworth

Richard Waldram

Eliot Walker

Patricia A Walker

Eve White

With thanks once again to all our generous supporters who have helped to fund this much needed resource for the Arboretum. If you would like to help support our ongoing Conservation, Education and Participation work, please consider making a donation today.

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