Penson Garden History Lecture 2026

This year's Penson Garden History Lecture could hardly have been more appropriately timed. As Oxford sweltered through a heatwave, recording its highest June temperature on record, even the short walk to the Auditorium highlighted one of the key messages of Kevin Martin's lecture on climate change and the future of our trees - how much cooler streets become when shaded by trees.

Kevin, who leads the tree collections at the Royal Botanic Gardens, Kew, described how climate modelling and ecological research are changing the way we think about tree planting. Rather than relying on what has grown well in the past, we now need to select trees that will thrive in the climate Britain is expected to experience over the next 50 to 100 years.

By the end of the century, South-East England is likely to be significantly warmer and much drier during the growing season, placing many familiar species under increasing stress. At Kew, modelling suggests that around half of the Gardens' 11,000 trees could become vulnerable if current climate predictions are realised.

We heard how Kew is using millions of plant records from around the world to identify trees better adapted to future conditions. Field expeditions to Romania, Georgia and other regions with climates similar to those expected in southern England are helping to identify species and seed sources with greater drought tolerance. The research suggests that some of our best future trees may come from these areas rather than from Britain's traditional woodland palette.

Kevin also revealed that over 70% of London's publicly owned trees may be vulnerable by 2100, underlining the importance of choosing the right species for future planting.

While the statistics sometimes seemed alarming, the lecture was ultimately optimistic in its discussion of how Kew is combining climate science with practical horticulture to develop tools that will help councils and gardeners plant the right trees in the right places for our changing climate.

Thank you to everyone who braved the heat to attend! Anyone who missed it can now watch the recording, available on our YouTube channel.