Gunnera – your questions answered

Everything you need to know following the introduction of new legislation around gunnera in UK gardens

What’s the problem with gunnera?

There are two large-leaved gunneras in British gardens that are difficult to distinguish. One of the species, the Chilean giant rhubarb (G. tinctoria), is a vigorous plant which has escaped to colonise extensive areas of Ireland and the western parts of the British Isles, as gunneras flourish in wetter, milder conditions. As G. tinctoria has a negative impact on native biodiversity, it has been banned under the Invasive Alien Species (IAS) Regulation and was banned in 2017.  
Why have the names changed?

Apart from G. tinctoria, the other large-leaved gunnera found in the UK was thought to be the Brazilian giant rhubarb (G. manicata). However, our research has shown that much of what is grown as G. manicata is actually a previously undescribed hybrid, G. × cryptica. This hybrid has the banned G. tinctoria as one parent and G. manicata as the other. As far as we are aware, G. manicata is no longer present in cultivation in this country.

Are plants being sold as Gunnera manicata actually Gunnera × cryptica?

The likely answer is yes, as this research suggests that the species Gunnera manicata appears no longer to be present in Britain and Ireland. The two original species, G. manicata and G. tinctoria, and the hybrid Gunnera × cryptica look very similar so differentiating between them is difficult, which likely explains how the hybrid went undetected for so long. The Brazilian species, G. manicata, seems to have been lost to cultivation a few decades after it was introduced in the Victorian period, leaving just the hybrid, which has been sold as the Brazilian plant ever since.

Why has G. × cryptica been banned?

Under the Invasive Alien Species Regulation, a ‘species’ includes any form of the species, including any hybrid with it. This has brought G. × cryptica under the regulations, so Defra has confirmed that it is also banned.

How invasive is G. × cryptica?

The hybrid produces few seeds, is only rarely found outside of gardens, and is not known to spread vigorously.  

How can I tell if I have G. × cryptica in my garden?

It’s hard to tell the different species apart. However, given that G. manicata is no longer present in UK gardens, if you have a large hardy gunnera in your garden, it will be either G. × cryptica or G. tinctoria. Both of these are banned and are covered by the same regulations around cultivation and disposal, so knowing exactly which species you have doesn’t really matter for understanding what to do.

What do I do if I have a large-leaved gunnera in my garden?

Current guidance from Defra for domestic gardeners is that any existing plants may be retained, but Gunnera × cryptica must not be newly planted or cultivated in gardens. We are currently seeking clarity from Defra on how ‘cultivation’ is defined in this context, so please check back on this page for updates. Any excess material from large hardy species, such as leaves cut back in autumn, should be disposed of either by burning on site or taking to a waste processing centre. Find out more

Are all gunnera species banned in gardens?

There are two other species of large-leaved gunnera – G. insignis and G. killipiana – but these are not hardy in most UK gardens.

There are small, mat-forming hardy species such as G. magellanica to seek out, which are great for wet soil on the margins of a large natural pond in gardens.

What can I grow instead of gunnera?

There aren’t any alternatives that provide all the same qualities as gunnera, particularly its giant size. However, there are a number of alternatives that gardeners can grow for umbrella-like leaves.
  • The closest replacement plant would be a more genuine rhubarb such as Rheum palmatum, which is most similar in appearance to the Gunnera manicata. Don’t forget this also gives you a delicious crop! It’s well worth seeking out varieties such as ‘Fulton’s Strawberry Surprise’, which produces sweet and tender crops of red stems from March right through to late summer.
  • The ornamental perennials Darmera peltata (umbrella plant) and Ligularia ‘The Rocket’ are also relatively large-leafed alternatives.
  • There are also half-hardy options, which may survive outside all year round in milder or urban areas. A canna will bring exotic drama with its dark foliage. Japanese bananas (Musa basjoo) also provide a tall canopy of large leaves.

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