When gardening, not all plants are your friends. Certain weeds – commonly known as ‘invasive plants’ or ‘garden thugs’ – are notorious for getting out of control. They can grow rapidly, outcompete native flora, damage structures and even pose health risks in some cases.
There are a few effective ways to battle these invaders. But before we look into that, let’s familiarise ourselves with some of the most common culprits.
The most common garden thugs
Many plants can be classed as invaders, but there are some shrubs that have become universally known for their rapid growth and tricky removal. Below are just a few of the plants that are worth looking out for.
Ivy
While ivy can make a beautiful decorative feature on walls, arches and pergolas, it can also be a nuisance if not tamed. This vigorous evergreen climber has been known to smother trees, pull down sheds and obstruct gutters. It can compete with other plants for nutrients and cause a dense mat that blocks out sunlight.
Nettles
Nettles can be found across the UK, often growing in thick patches. They grow rapidly and quickly outcompete flowers and vegetables. They tend to also harbour pests like aphids. On top of this, their stinging hairs can make areas inaccessible to both humans and animals.
Mint
Many people have made the mistake of growing this popular garden herb, only to discover that their garden is suddenly overtaken with mint leaves. Varieties like spearmint are known to spread aggressively and stifle other plants. If not contained, you’ll be left with a mint carpet.
Japanese knotweed
One of the UK’s most notorious non-native invaders is Japanese knotweed. It can grow almost anywhere and when it does take hold it can grow up to three metres while creating a stubborn root system that is hard to remove. Keep an eye out for its red-purple shoots and spade-shaped leaves
Bamboo
A lot of first-time gardeners are drawn to the exotic appearance of bamboo. However, this grass’s rhizomes can travel metres underground causing it to sprout up in unexpected places all across one’s garden. It also grows very fast, making it hard to keep on top of. Phyllostachys is one of the most fearsome varieties.
Himalayan balsam
Although its pink flowers can be pretty in summer, Himalayan balsam is also known for scattering seeds everywhere. You’ll find these plants sprouting all over your garden. They particularly love damp areas, river banks and pond edges.
Russian vine
Also known as ‘mile-a-minute’, this rampant climber regularly overwhelms UK gardens once it takes hold. Its white flowers make it quite an attractive plant, but it can quickly outcompete other plants until it’s the only species there. Like ivy, it can also cause structural damage.
Giant hogweed
Giant hogweed isn’t just invasive, but dangerous – its sap can cause severe burns and blisters on contact. It forms dense colonies, grows tall and kills off other plants by stealing sunlight and water. Look out for its distinct white umbrella-like flower heads.
Bindweed
This persistent perennial can be a formidable foe. It has deep roots, seeds prolifically and can regenerate from the smallest fragment. Fail to control it, and it will wrap itself around other plants in your garden and cause an impenetrable shroud.
How to fend off these invasive plants
Once you’ve identified invasive plants, your next step is removal and protection. There are a few practical tips that will help you tackle these invaders. The best defence may depend on the type of plant.
Regularly cut back
Creating a routine for cutting back plants can help to prevent your garden becoming an overgrown jungle. For weeds like nettles, try using a weed wacker to trim them back. For climbers like ivy and Russian vine, use secateurs every few weeks between Spring and Autumn. Regularly trimming can weaken many plants and may eventually cause them to die off, but you need to be persistent.
Dig out at the roots
Thoroughly removing some plants involves physically digging out the roots. With deep rooted invaders like bindweed and Japanese knotweed, you may have to do a lot of excavating. You can loosen soil with a fork. This method is best suited to small clusters rather than large areas, as it can be labour-intensive and time-consuming.
Use herbicides
Herbicides are a powerful tool against stubborn plants, but you must use them judiciously. Carefully target plants so as to not damage shrubs that you actually want to preserve. Glyphosate-based herbicides approved for amateur use are your best choice – apply on a calm day to avoid drift. There are many guides online that can help you to compare weed killers.
Contain in pots
If you really want to grow mint or bamboo, but don’t want it to take over your garden, consider growing these plants in pots. This helps to contain their spread by stopping roots from getting too far Prolific seeders are often best placed on patios away from any other plants to prevent them repopulating elsewhere. Make sure pots are large enough to support the plant’s growth.
Use root barriers
Root barriers are an excellent defence against plants with deep root systems like bamboo and Japanese knotweed. These are tough plastic or fabric membranes that are buried around a plant 1 or 2 metres deep. Dig a trench, insert the barrier and backfill securely. While root barriers are effective ways to contain plants, they are not easy to install and may not be appropriate if you’re trying to isolate multiple plants.
Know when to get professional help
Not all invasive plants are suitable for DIY removal. When removing hazardous plants like giant hogweed, it’s often safer to call in professionals who can remove the plant without getting injured. Widespread infestations of plants may also be better left to a pro to save you time and energy. An experienced gardener is more likely to have the knowledge and tools to efficiently deal with such plants. You can also call upon experts when it comes to installing root barriers.
