Responding to climate change at Ham House

The Cherry Garden at Ham House and Garden, London — The Cherry Garden at Ham House and Garden | © National Trust Images/Chris Davies

The garden at Ham House is rooted in centuries of history but the effects of climate change mean that it now faces its biggest challenge. Find out how we’re adapting to changing weather patterns, reducing carbon emissions and addressing the damage that's already been done.

How climate change is impacting Ham House

The effects of climate change are having a serious impact at Ham House. Extreme weather, unpredictable rainfall, drought and flooding are all taking their toll on landscapes and buildings. There is now a 10-25% chance of a heatwave each year, compared to a less than 10% chance a decade ago.

Ham House's position on the banks of the Thames makes it vulnerable to flooding as heavy rainfall causes the river to overflow. It’s not just rain that causes issues. Drier weather during spring is affecting blossom, fruit and young plants and has also seen an increase in pests and diseases. Soaring temperatures are drying out the soil and scorching plants that once thrived in the walled garden.

The South Terrace in spring at Ham House and Garden, London — The South Terrace in spring at Ham House and Garden | © National Trust Images/Chris Davies

Adapting Ham House garden to face climate change

The changes we’re making to Ham House's garden is the biggest intervention we’ve made since 1975. The extremes of temperature we're experiencing mean that it is facing some danger, but it’s also an opportunity to rethink and consider ways of running the garden more sustainably.

Visitors to Ham House are part of the changes too. To ensure visitors can enjoy the garden during particularly high temperatures, the benches are moveable so we can change the positions around the garden and so some are always in the shade.

Propagation volunteers at work in the polytunnel at Ham House and Garden, London — Propagation volunteers at work in the polytunnel at Ham House and Garden | © National Trust Images/Chris Davies

How are the plants changing?

We’ve seen much more frequent flooding at Ham House over the last five years and as a result, the trees that we plant need more care and management. Extra care is also vital during periods of spring drought and intense summer heat.

We’ve planted a lot of apple trees in the garden because they can thrive in a variety of climates. Our mix of apples include local and modern varieties. The diverse mix has a strong resistance to certain diseases.

Heat and humidity at Ham House 

The rapid increase in heat and humidity could result in 40C days becoming common by 2040, and the head gardener now ‘applies a climate change perspective to every single action in the garden’.

This means altering the types of plants introduced to include those more resilient to high temperatures, such as cannas and agaves. A Mediterranean diet of outdoor-grown aubergines, chillies and a long tomato season could become the norm.  

What about the water that Ham House uses?

Water usage is an important consideration in the National Trust’s climate change plans, and it also has a crucial role in the large gardens that we care for. Ham House only uses water harvested on site with a Victorian irrigation system. Rainfall from the house guttering is collected in water chambers that irrigate through the rest of the garden. Collectively, these changes will protect Ham House against climate change for future generations.

Tackling climate change at Ham House

Over the years staff and volunteers have lovingly tended the garden and they are working hard to tackle the effects of climate change. From using Victorian irrigation systems to planting more resilient species of trees and plants, a number of measures have been taken to protect Ham House for future generations.