Getting Rid of Gunnera Plants

Credit: Drew Avery

Q: How do I remove a Gunnera plant from my garden? I tried to dig it out but the roots are five-inches thick. Can I kill it and let it rot? How would I go about doing that?

Thank you for your help.

It’s the first time I’ve heard of anyone wanting to get rid of a “Giant Rhubarb” (Gunnera manicata or G. tinctoria). Moreover, these plants are generally not very winter hardy without heavy mulching. Instead, Gunnera love boggy conditions.

I would suggest trying to expose as much of the roots as possible to cold winter air. You can do this by removing the soil from around the roots. Try to also reducing the amount of soil moisture by keeping the roots drier.

If systemic herbicides are an option for you, consider painting them onto an exposed cut root surface – this should weaken the plant. Also, deep mulching – to a minimum of 20 cm (8 in.) – and continually cutting off new shoots should work.

In any case, it will take time, persistence and patience to kill off this Gunnera.