5 thuggish plants that experts say will take over your garden if you're not careful

Thuggish plants that will take over your garden may sound like something from a horror film (Day Of The Triffids, anyone?), but the truth is far more mundane... and irritating.

Yes, while we all know that there are invasive plants you should avoid planting in your garden, there are a number of fast-growing bullies that it’s worth being aware of, too. While they’re not bad for the environment, they can be bad news for a carefully planned planting scheme, mainly because they have the potential to get quite big in a surprisingly short period of time.

These overzealous garden invaders can smother your best perennials, hog all the nutrients in the soil, and ruin the vibe you’ve worked so hard to cultivate in your outdoor space. So, which ones are worth keeping an eye on?

The thuggish plants that will take over your garden

Most homeowners immediately think of Japanese knotweed when talking about invasive plant species. Still, 'it's worth flagging that the term "thuggish" can be a bit tricky,' says award-winning garden designer Zoe Claymore.

'Often, people want low-maintenance plants, which by default means choosing more resilient species. But resilience can often come hand-in-hand with aggressiveness. You can’t always have your cake and eat it; many so-called easy-care plants will take over if left unchecked.'

Zoe Claymore

Zoe Claymore is a multi award-winning garden designer based in London. She focuses on creating outdoor places with emotional connection and ecological integrity for her private and commercial clients.

With that in mind, then...

1. Spanish bluebells

You might not expect to see them on a list of thuggish plants that will take over your garden, but bluebells – specifically Spanish bluebells – are a firm no from many garden experts.

'I’d never use Spanish bluebells,' says Zoe, who points out that these unscented blooms pose a huge threat to our native bluebells.

Take care, then, to stick to planting English bluebell bulbs (like these ones from Sarah Raven) when you're designing your own woodland garden.

2. Acanthus

A cottage garden staple, acanthus (also known as bear's breeches) is a beloved herbaceous perennial that can tolerate most planting conditions... albeit a little too well.

Noting this is one of those unexpectedly thuggish plants that will take over your garden, Zoe says she will still 'use acanthus if someone specifically wants to plant up a dry, shady spot'. She would, however, take care to plan exactly where it's going, as this one has very deep roots which are hard to remove once established.

3. Bamboo

It's important to research the realities of bamboo if you plan on using it as a garden screening plant, as this is absolutely one of those thuggish plants that will take over your garden if you're not careful.

'While it's fashionable in modern garden design and undeniably striking, bamboo can be a menace if not properly contained, ' says landscaper and gardening expert Steven Bell.

Steven Bell

Steven Bell is an experienced landscaper, with years of experience owning paving and gardening companies. Combining hands-on expertise with a deep appreciation for sustainable landscaping practices, Steven enjoys sharing his insights with readers to inspire their own green-thumb adventures.

Noting that 'many species send out creeping underground runners that can pop up metres away from where you originally planted it, even pushing up through patios', Steven says the fix is simple enough.

'Take care to only grow clumping varieties (like Fargesia) in large pots or install a solid root barrier at least 2 feet deep. Never trust bamboo without a plan!'

Try something like Todds Bamboo Root Barrier from Amazon if your heart is set on planting bamboo, then.

4. Mint

The innocent-looking spearmint from Crocus seen above (and all other varieties of mint) have the potential to become one of the thuggish plants that will take over your garden, if you're not careful.

'I’ll only ever put mint in pots, never directly into the ground, because it spreads so aggressively,' says Zoe.

Whether you plan to grow mint from seed or try your hand at growing mint from cuttings, then, be sure to have a pot handy.

5. Ivy

Perfect for even very tricky north-facing gardens, it's little wonder that ivy garden ideas are trending right now. Still, it's important to remember that this glossy evergreen has earned a place on our list of thuggish plants that will take over your garden.

'English Ivy is a classic, but left to its own devices, it will climb walls, strangle trees, and blanket everything in sight. It's often sold as a quick ground cover, but that quickness can become a curse if you’re not on top of it,' says Steven.

'Regular pruning is essential,' he adds, noting that 'ivy has its place, but only if you’re willing to keep it in check like a Victorian headmaster'.

FAQs

What is the most difficult plant to get rid of?

The most difficult plant to get rid of is the poster child of plant thuggery: Japanese Knotweed.

'Infamous in the UK, and for good reason, it can grow through concrete, damage property foundations, and is so aggressive that it’s a legal issue when selling a house,' says gardening pro Steven Bell.

'What starts as a lovely tall bamboo-like shoot becomes a monstrous underground network of rhizomes that are incredibly difficult to remove, so avoid or remove immediately. If you suspect it’s lurking near your property, call a professional. This is not one for DIY.'

Steven adds that ground elder also 'spreads through a vigorous web of roots and will quickly dominate borders, choking out more delicate perennials'. Similarly, the popular 'Montbretia (especially the common hybrid) spreads via corms and can crowd out other plants in no time'.

'Once it’s in, it’s really in,' he stresses.

Which plants will take over your garden?

While it's easy to list off all the banned invasive plant species in the UK, there are some unexpected plants that will take over your garden to be aware of, too – including mint, Spanish bluebells, bamboo, and ivy.

'I know a designer who’s stopped using Erigeron karvinskianus because it can travel far beyond where you planted it,' says award-winning garden designer Zoe Claymore. 'And another one to keep an eye on is wild garlic. I actually quite like it, so long as you commit to editing it yearly, as it really can take over.'

She adds that 'rhododendron ponticum is another big issue. It's very much out of fashion now, particularly in ecological garden design, as it blocks out all the light, so many designers are replacing it with a mix of woodland shrubs and small trees; things like viburnum opulus, hazel, spindle trees, and ferns.'

It's also a good idea to swerve planting anything like a leylandii hedge if you aren't big on pruning, as they are prone to getting absolutely massive in a very short space of time.

Now that you know the thuggish plants that will take over your garden, you can set to figuring out a planting scheme that avoids them entirely (or keeps them contained in pots, if you prefer).

Happy planting, and stay vigilant!