The Gunnera manicata, more commonly known as giant rhubarb, which grows along the Woodland Walk, is perhaps one of the most eye-catching plants growing here at Winterbourne. It has enormous umbrella-like leaves, which grow up to two metres wide and sit atop thick stems covered in spikes of red and green.

A Jurassic giant with a complicated past

We grow several species of Gunnera at Winterbourne, including Gunnera manicata, Gunnera tinctoria, and Gunnera magellanica. These unusual plants, which look a bit like something from the Jurassic period, are believed to have been planted at Winterbourne by John Nicolson in the 1930s. A photograph of John standing next to the Gunnera manicata, captured in 1937, seems to show his pride and fascination in these exotic plants. What he didn’t know at the time, however, was that they posed a threat to the native plants also growing along the Woodland Walk.   

Thriving in wet and mild conditions, the Gunnera tinctoria species colonised large parts of Ireland and the western parts of the British Isles. Their invasiveness overwhelmed native species, and the crossbreeding of different varieties of Gunnera meant that almost all plants previously thought to be Gunnera manicata were in fact Gunnera tinctoria. As a result, in 2017 various species of Gunnera plants were banned, making it an offence to plant or grow them in the wild, or to sell them in this country.

But don’t worry, pre-established plants like ours are allowed to remain so long as they are kept carefully under control. Whilst we wouldn’t want the Gunnera to colonise the native species growing around the garden, they do represent an important part of Winterbourne’s history, so we go to great lengths to both control and protect the plants.

Taking care of these plants today

Last month, Outdoor Area Supervisor, Will, stepped into his wetsuit and ventured into the boggy and marshy waters of the pond at the base of the garden for the annual chopping back of the Gunnera.

Using a pruning saw, he easily sliced off the gigantic leaf, stopping it from seeding. The leaves can then be used to create the perfect winter blanket for the roots to protect them from frosts throughout winter. If you head down to the Woodland Walk on your next visit, you’ll spot the leaves lying on top of the buds of the plants, held into place with their spear-like stems.

Thanks to the care taken by the garden team in this annual process, the Gunnera continue to delight visitors today, even as we approach 100 years since the species were first planted at Winterbourne.

Head to our Instagram and Facebook to see Will in action, chopping back the Gunnera.