“A society grows great when old men plant trees in whose shade they shall never sit.” – Greek Proverb
At Chelsea Physic Garden, we look back with gratitude at our forebears who planted the ginkgo, the mighty holm oaks, and the manna ash, as well as the 189 other trees that populate our canopy. We are home to 158 tree species, across 102 genera, from across the globe, collected and cultivated over three and a half centuries.
As contemporary custodians of the Garden, as we look to the future, the main question we must ask is not whether to plant trees, but which trees to plant. Firstly, this means knowing which species are likely to fall foul of changing climates, pests and diseases, or simply old age, and which trees will survive and thrive in our enclave on the Thames.
Last year, the Garden lost 4 trees last, and planted 2, further prompting the need to do more research and create a tree planting succession plan to safeguard the Garden for the future.
Thanks to a generous donation from an individual donor, we have taken the first step: understanding what we already have. Treeco₂nomics were commissioned to study the structure and composition of our trees and calculate their value in terms of ecosystem services.
What does this mean?
Trees are incredibly valuable, not only for shade, aesthetics, and for the survival of plant and animal life, but to carbon storage and sequestration, rainwater runoff, and air pollution removal. The absence of trees at the Garden would result in higher temperatures, flooding, and low air quality. These are the ecosystem services that trees provide to any given area, to the benefit of plant and humankind.
What does it tell us?
The amenity value of our trees is £8.7million, and they provide the Garden and surrounding area with a range of ecosystem services:
Carbon storage
52.6 tonnes
OR
8 elephants
Annual carbon sequestration
2.4 tonnes
OR
5 Grand Pianos
Rainwater run off
101m3
OR
150,000 large coffees
Leaf area
3.5 hectares
OR
½ of Buckingham Palace
The data gathered by Treeconomics provides a baseline for future modelling and planting. We can use BGCI’s Climate assessment of trees tool to help inform us about the suitability of our species for warmer climates.
For example, modelling shows us that tree species that do well in southern Georgia in the Caucuses or southern Spain, will thrive here by 2050. In contrast, trees such as Sorbus aucuparia, Rowan, will come under stress in our microclimate, regardless of being under the expert care of our botanical horticulturalists. 2025 was the warmest, dryest year on record and we will certainly be seeing the impact of that stress on our canopy over the next 2 to 5 years.
Our next step is to work with tree experts to develop a Tree Succession Plan, so we can welcome new species to the Garden whilst managing the decline of others. We are pleased to report that 78% of our trees are in excellent condition, but since their growth is slow, we must act fast to ensure our tree collection survives in the future.
As we develop our tree succession plan, we are spotlighting a tree each week, from pomegranate to pine, and cork oak to conifer. Keep an eye on our social media and join us for some tree talk!
