Blog: Familiar huge-leaved variety now ‘of special concern’
A blow for gardeners who love big leaves, Gunnera or giant rhubarb, is to be banned by the UK government, similar to Japanese knotweed. This means it cannot be sold or cultivated. If you have it in your garden, you must ensure it does not spread into the wild.
Much loved by gardeners who have the room to show off its impressive 2m leaves, you’ll see it in many large gardens, especially growing in damp areas or beside water. The problem with the plant has been uncovered by new research from the RHS, published in the journal Sibbaldia.
Gunnera or giant rhubarb banned – We’ve been living with an evil hybrid!
It turns out that the plant we thought was Gunnera manicata, a harmless plant originating in Brazil and Chile, is nothing of the sort. There is another, far more sinister variety, G. tinctoria. This is highly invasive and crowds out native plants. It has been illegal to sell or cultivate G. tinctoria since 2017.
Unfortunately, the new study revealed that the original G. manicata was lost to cultivation soon after its introduction. I’m sure with some horror, researchers found a hybrid between G. manicata and G. tinctoria, now named Gunnera × cryptica. This hybrid has inherited the bully boy tendencies of the most aggressive parent, so it will now be banned.
As the plant is so widespread – and you were able to find it in many large garden centres – there are fears the widespread nature of this plant will cause problems. Parent G tinctoria has spread in wetter areas in Western Ireland and Scotland. It has been listed as a “species of union concern” under EU regulations and is listed as being of “special concern” in the UK.
Gunnera or giant rhubarb banned – removing plants
Defra says the hybrid should be treated as a banned species. However, any existing plants can be kept, but Gunnera × cryptica must not be newly planted or cultivated. In drier areas, the plant needs a lot of watering, and this falls under the definition of cultivation, so many plants will die out this way. I once tried to grow one in a large pot. It hated the conditions and soon gave up the ghost, so that’s one way to go!
The RHS is changing its advice to gardeners about G. manicata plants, which are almost certain to be invasive hybrids, removing them from sale, and identifying plants in its gardens. While some may be removed from RHS gardens, any remaining plants will be identified with advice on not to plant them.
The RHS advice on removal – cut the plant back and use a herbicide. I don’t like the use of herbicides, so I would go down the other route – dig it out. Stop it from spreading by cutting off flower heads each summer before they set seed. Either compost with care or burn. Cut flower spikes close to the base with a pruning saw in July or August.
Gunnera varieties you can safely grow
While Gunnera tinctoria and G. × cryptica can no longer be planted, existing plants can stay in your garden. Any plant material should be burned at home. However, smaller varieties G. insignis, G. killipiana, can be grown. The downside? They’re not hardy in most gardens.
You can try G. magellanica, also known as the devil’s strawberry. It has much smaller leaves but is reliably hardy down to -10 °C. In prolonged cold spells, expect frost damage to leaves and stems, but these should regrow. For other big-leaved plants to try instead, read my guide to the best available.
Gunnera or giant rhubarb banned in the UK after study updated 2025
