Gunnera plants or Giant Rhubarb, those magnificent leafy giants, have been banned in the UK following publication of a recent study. The news of the Gunnera plant ban has taken the gardening community by surprise. Known for their exotic appearance and impressive size, these plants have been a firm favorite among many. However, due to their aggressive growth and potential threat to the environment, the UK government has banned the cultivation and sale of Gunnera.
So, what should you do if you already have Gunnera plants in your garden? And what alternatives can you consider to fill that void? In this article, we will provide you with all the information you need to navigate this ban and ensure your garden remains vibrant and lush. Stay informed, stay compliant, and keep your garden thriving!
Why Gunnera plants are banned in the UK
The ban on Gunnera in the UK is a result of the discovery of a new hybrid species, Gunnera x cryptica. Until this discovery Gunnera manicata, a non-invasive species, was thought to be the variety commonly grown in gardens. Recent DNA research and morphological analyses with the help of botanists from South America has shown that what was believed to be Gunnera manicata is actually a hybrid of Gunnera manicata and Gunnera tinctoria.
Gunnera tinctoria is highly invasive, and has been banned under UK and EU regulation since 2017, when it was added to the EU List of Invasive Alien Species of Union Concern. After separating from the EU, this regulation was adopted into the UK legislation and all species listed as of EU concern are termed species of Special Concern in the UK.
Gunnera x cryptica has a similar growth habit and has inherited some of the invasive features of the parent species Gunnera tinctoria. This has led to the classification of large-leaved Gunnera, commonly known as giant rhubarb, as invasive.
The UK government has decided to ban the cultivation and sale of these plants following advice from the Department for Environment Food and Rural Affairs (DEFRA). DEFRA consider that hybrids of listed plants should also be banned, which is why this previously undetected hybrid has been allowed in UK gardens up until now. The discovery of the new hybrid and reclassification of Gunnera manicata to Gunnera x cryptica is the triggering event for the ban.
The invasive nature of Gunnera plants
Gunnera plants are native to South America but have been widely cultivated in other parts of the world, including the UK. Once established, mature plants can shade out or suppress native plants, leading to a reduction in biodiversity.
Gunnera tinctoria plants have a tendency to spread rapidly and form dense colonies, overtaking native vegetation and disrupting delicate local ecosystems. Their invasiveness accelerates in wet and humid environments that are similar to their native habitats, allowing them to outcompete native species.
Research suggests that Gunnera tinctoria, in particular, modifies soil biotic communities and influences soil physicochemical characteristics, further impacting the ecosystems they invade.
So how invasive is this previously undeteted hybrid, Gunnera cryptica? The researchers state that it rarely reproduces by seed, and appears not to spread as rapidly as Gunnera tinctoria, but that they can’t rule it out as an invasive threat.
Legal implications of owning Gunnera plants in the UK
If you currently own Gunnera plants in the UK, it’s important to understand the legal implications of the ban. The ban on Gunnera plants in the UK prohibits both the cultivation and sale of these plants. While the ban prohibits the cultivation and sale of Gunnera plants, it does not explicitly address the possession of existing plants.
DEFRA advise that existing plants do not have to be removed, but you cannot plant new plants in your garden or purchase G cryptica or G tinctoria from nurseries or other sources. However, watering and actively tending to the plant are technically cultivation, so the Royal Horticultural Society recommend that you take proactive steps to remove Gunnera plants from your garden.
The RHS will be working closely with garden centers and national trust properties to ensure that they are complying with the regulations.
How to identify Gunnera plants
To ensure compliance with the ban, it is crucial to be able to identify Gunnera plants accurately. Here are some key characteristics to look for:
Large, lobed leaves
Gunnera plants feature distinctive large leaves, which can measure up to six feet (1.8 m) in diameter. These leaves have a round shape and are deeply lobed, resembling the leaves of rhubarb plants. The leaf stalks are long and thick, supporting the weight of the leaves.
Stout, prickly stems
The stems of Gunnera plants are stout and can grow up to ten feet in height. Prickles coat the stem, which provides protection against herbivores. The stems have a reddish-brown color and are capable of supporting the weight of the massive leaves.
Cone-shaped flower spikes
During the summer growing season, Gunnera plants produce cone-shaped flower spikes that can reach up to six feet in height. Small reddish-green flowers cover these flower spikes.
What to do if you already own Gunnera plants
If you already have Gunnera plants in your garden, it’s time to take action to ensure compliance with the ban. An easy way to kill off Gunnera plants is to cut off all leaves and flower spikes at the base of the plant and treat the remaining crown with a herbicide. Follow the manufacturer instructions and wear safety equipment as the leaves are prickly.
Alternatively, you can dig out the plants. Start by trimming all the leaves to the base. The next step is digging out the plants along with their extensive root systems. Take care to remove as much of the root system as possible to minimize the risk of regrowth. After removing Gunnera plants, monitor the area for any signs of regrowth. Gunnera plants are resilient, and even small fragments can lead to their resurgence. If you notice any new growth, promptly remove it to prevent the spread of the plants.
If you decide not to remove your Gunnera plant, at least remove the flowering spike before it can set seed. Cut the spike off as close to the base as you can using a sharp knife or pruning saw. Removing the flower spike prevents further spread of the plant.
Alternatives to Gunnera plants for UK gardens
Gunnera have long been a popular garden plant and feature prominently in the grounds of stately homes and private gardens. Although Gunnera plants are now banned in the UK, there are plenty of alternative options available to add beauty and interest to your garden. Consider the following alternatives:
Rheum palmatum (Ornamental Rhubarb)
Ornamental Rhubarb, also known as Rheum palmatum, is a stunning alternative to Gunnera plants. It shares similar characteristics, such as large, palmate leaves and tall flower spikes. This plant adds a touch of drama to any garden while remaining non-invasive.
Ligularia dentata (Leopard Plant)
Leopard Plant, or Ligularia dentata, is a herbaceous perennial that thrives in moist, shady environments. It features large, bold leaves with attractive serrated edges and produces clusters of bright yellow flowers. This plant only reaches heights of 2-4 feet (0.6 – 1.2 m).
Rodgersia pinnata (Featherleaf Rodgersia)
Featherleaf Rodgersia, or Rodgersia pinnata, is another excellent choice for UK gardens. It boasts large, palmate leaves and produces elegant plumes of pink or white flowers in the summer. This plant thrives in moist soil and partial shade.
Colocasia esculenta (Taro)
Taro, with its large, heart-shaped leaves, provides a tropical feel and is well-suited for wet environments. It’s a good choice if you are looking to match the height and leaf size of Gunnera.
Resources for more information on UK plant bans
For further information on UK plant bans or to educate yourself about invasive species, consider the following resources:
- Royal Horticultural Society (RHS) The RHS provides comprehensive information on plant bans and invasive species in the UK. Their website offers guidance on identifying and managing invasive plants, as well as resources for alternative plant choices.
- Plantlife Plantlife is a UK-based charity dedicated to the conservation of wild plants and their natural habitats. They have valuable resources on invasive plants and their impact on native flora and fauna, along with tips for gardeners.
- Local authorities and environmental agencies Contact your local authorities and environmental agencies for specific information on plant bans in your area. They can provide guidance on local regulations and offer advice on environmentally-friendly gardening practices.
Taking action to protect the environment
The ban on Gunnera plants in the UK is a necessary step to safeguard native flora and fauna. By understanding the reasons behind the ban, the potential risks associated with Gunnera plants, and the alternative options available, we can make informed decisions as gardeners. It is our collective responsibility to protect the environment and ensure the sustainability of our gardens. Let’s embrace the ban, remove Gunnera plants from our gardens, and explore alternative choices to create beautiful, thriving spaces that support native wildlife and enhance biodiversity. Together, we can make a difference and preserve the natural beauty of our environment, no matter where we live.
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Reference:
Edwards, D., Armitage, J., Bilsborrow, J., David, J., Gebauer, M., Hassemer, G., … Könyves, K. (2023). An investigation of large-leaved Gunnera L. (Gunneraceae) grown outside in Britain and Ireland. Sibbaldia: The International Journal of Botanic Garden Horticulture, (22). Retrieved from https://journals.rbge.org.uk/rbgesib/article/view/1998
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