If your garden is glowing with sprays of orange flowers at this time of year, you may have montbretia growing among your borders.
Also known as Crocosmia × crocosmiiflora, montbretia is widely suited to UK gardens and very easy to grow, which has helped it spread to hedgerows, riverbanks, woodland edges and waste ground across Britain. Today, the RHS lists Crocosmia × crocosmiiflora as an invasive non-native species in the UK.
Here’s everything you need to know about spotting and managing montbretia in your garden.
What is montbretia, the common invasive plant?
Montbretia has been a garden plant in Britain since the Victorian era. Its flowers arrive when many summer displays are beginning to fade, and established clumps can return year after year with very little attention.
According to the GB Non-Native Species Secretariat, the danger of montbretia is that it can dominate habitats and exclude native species.
It is also included on Schedule 9 of the Wildlife and Countryside Act 1981, which means it is an offence in England and Wales to allow montbretia to spread beyond your own land and into the wild.
How to identify montbretia in your garden
Montbretia is easiest to identify once it flowers. The plant usually grows to around 60cm tall and has upright leaves with a flat, spear-like shape. From summer onwards, arching flower stems carry clusters of orange, tubular flowers.
It grows from underground corms similar in appearance to bulbs, and established plants tend to develop into increasingly substantial clumps.
During winter, the foliage dies back. The GB Non-Native Species Secretariat suggests looking for old rusty-brown leaves and the remains of previous flower stems when identifying patches outside the flowering season.
Montbretia and the law in England and Wales
Finding montbretia in your border does not equate to a legal crisis. According to the Wildlife and Countryside Act 1981, it can still be grown in a garden – the legislation makes it an offence to plant it or cause it to grow in the wild. So throwing unwanted corms or plant material over a garden boundary, into a hedgerow or onto waste ground could count as an offence.
How to control montbretia in your garden
Montbretia is relatively straightforward to remove by hand from garden borders.
A few practical steps make the job more effective:
- Dig around the entire clump. Use a garden fork or hand fork to loosen the soil around the plant and lift the underground corms carefully.
- Check the loosened soil for remaining corms. Small pieces left behind can produce fresh growth, so work through the area thoroughly.
- Keep an eye on the patch afterwards. Any new shoots give you a useful clue that underground material remains. Lift them promptly and check the surrounding soil again.
- Avoid moving unwanted plants around the garden. Transferring soil containing corms can move the plant to a fresh bed.
- Do not add corns to home compost. They may survive the composting process and then spread when that compost is used elsewhere in the garden.
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