Fun fact about me? I’ve lost count of the number of times I’ve enthusiastically planted something I’ve picked up at my local garden centre that’s been described as ‘easy’, ‘reliable’, or ‘perfect for filling gaps’, only to spend the next few years quietly trying to rein it in.
As a gardens editor, I’m constantly trialling plants that promise low-effort impact (much to my husband’s perennial despair). Some of the most widely recommended varieties, however, have turned out to be the most surprisingly destructive plants. And by surprising, I mean that these aren’t the same old invasive plants we know to steer clear of.
Still, you don’t have to be planting Japanese knotweed (don’t! Not ever!) to be making a major garden design mistake. Sometimes the culprits can be found lining the shelves of garden centres, suggested in planting schemes, and praised for their ability to spread. And that’s exactly the problem.
Surprisingly destructive plants to avoid
So, what do I mean by surprisingly destructive plants? Well, I guess I mean the ones that promise to spread quickly, because that doesn’t always mean politely bulking out a border.
In many cases, in fact, it means staging a quiet takeover; think creeping into lawns, smothering neighbouring plants, and proving far harder to remove than you’d expect. They’re the quiet grafters that can quickly become garden bullies. And a bully is always a bully in my opinion, no matter how pretty they might look.
So while I wouldn’t call them mistakes exactly, they are the surprisingly destructive plants I now approach with extreme caution. From charming cottage garden favourites to fragrant ground cover, here’s what I personally wouldn’t grow again (as well as what I’d choose instead).
1. Hardy geraniums
I know, I know; this one feels controversial. Hardy geraniums are often recommended as the ultimate easy filler, and in many ways, they are. But that’s exactly why I’ve fallen out of love with them.
Once established, some varieties can spread far wider than intended, and I’ve found they can be particularly tricky to edit out once they’ve settled in, as they tend to knit themselves into the root systems of everything around them. Which is less than ideal.
Grow instead: astrantia
If you love that relaxed, cottage garden feel, astrantia gives you the same softness but in a much more controlled, clump-forming way. Something like the Astrantia ‘Buckland’ from Crocus will come into bloom earlier than many of the other cultivars.
2. Japanese anemones
There’s no denying how beautiful Japanese anemones are in late summer, when so much else is starting to fade. But they’re one of the biggest “right plant, wrong place” offenders I’ve come across, which can make them surprisingly destructive plants if you aren’t careful.
Once they’re happy, they spread via underground runners and can pop up unexpectedly throughout the border. I’ve had them appear several feet from where they were originally planted, pushing through other plants and making spacing feel completely unpredictable.
Grow instead: echinacea
For late-season colour that stays exactly where you put it, echinacea is a much more reliable choice… and just as impactful. I personally love the classic pink echinacea purpurea variety, £7.99 at Crocus.
Crocus
Echinacea Purpurea ‘white Swan’
This echinacea boasts pretty white blooms from June to September.
Crocus
Echinacea ‘flame Thrower’ (pbr)
If you want bold colour, you can’t go wrong with the Echinacea ‘Flame Thrower’.
Crocus
Echinacea Purpurea
A pollinator magnet, this long-flowering bloom can handle almost any bad weather.
3. Mint
This is one I always warn people about now. Mint is one of my absolute favourite herbs, but it has absolutely zero respect for boundaries when planted in open soil.
It sends out runners in every direction, quickly infiltrating beds and taking over the space you intended for other plants. I’ve seen it travel under paths and emerge on the other side, which tells you everything you need to know… which, yes, earns it a place on my list of surprisingly destructive plants.
Grow instead: mint (just do it in a pot!)
Mint is great! Just keep it contained, okay? Try something like this chocolate mint variety from Crocus for something a little different.
4. Hops
Hops are often sold as a fast-growing climber to cover fences or structures, and they absolutely deliver on speed (and scent, actually; crush one between your fingers and give it a whiff). The problem is, they don’t really know when to stop.
In my experience, they can quickly overwhelm their support, scramble into nearby plants, and create a dense, tangled mass that’s difficult to manage. My husband keeps trying to make it happen in our garden, and I spend most days going out and unwinding it from my lilac and other shrubs. It’s a full-scale operation, and I don’t recommend it.
Grow instead: Clematis (viticella types)
Clematis give you that same vertical interest and coverage as hops, but with a lighter touch and far less chaos. Try the Clematis Blue River (‘Zoblueriver’) (PBR) from Crocus for stunning romantic blue blooms.
Crocus
Clematis Blue River (‘zoblueriver’) (pbr)
We love this one’s small, star-shaped, purple-blue flowers.
4. Periwinkle
Periwinkle is often marketed as an easy evergreen ground cover, especially for tricky spots (in fact, it’s often touted as one of the best shade garden plants around). And while it does cover ground quickly, that speed can become a real issue.
It forms dense mats that can smother smaller plants and is surprisingly persistent if you try to remove it. I’m fine with that, personally, but I’ve had family members who have forged longstanding vendettas against periwinkle for this exact reason.
Grow instead: Coral bells
Coral bells offer colour, texture, and ground-cover potential without the same aggressive spread, making them a much more design-friendly option. I’m very fond of Heuchera ‘Autumn Leaves’ (available at Crocus) if you’re wondering.
5. Leylandii
Leylandii isn’t technically invasive, but it causes enough garden misery to earn a place on this list (just ask JK Rowling, who earned that lesson the hard way!). It’s often sold as a fast solution for privacy, and to be fair, it does deliver… just not always in a manageable way.
Yes, keeping it under control requires regular, committed pruning, and if that slips for even a moment, then it can feel like the hedge takes over entirely. All of which means that this is one of those surprisingly destructive plants where the maintenance burden rarely matches the initial promise. If you don’t have the time (or inclination) to stay on top of it, it will absolutely punish you for it.
Grow instead: Yew
For a more elegant, slower-growing hedge that responds well to pruning and keeps its shape beautifully, yew is a far more forgiving choice. Try this English Yew from Crocus.
FAQs
What is Britain’s most poisonous plant?
One of the most poisonous plants in Britain is actually Aconitum napellus, also known as monkshood. It’s a striking, architectural perennial often grown in borders, but every part of it is highly toxic. Even handling it can cause reactions in some cases, so take care.
What are the most invasive plants in the UK?
When we talk about truly invasive plants in the UK, the main villains are Japanese knotweed, giant hogweed, and Himalayan balsam, as these are the ones that spread aggressively in the wild, outcompete native plants, and are subject to legal controls.
Spanish bluebells, however, are slowly earning themselves a spot on this list, as they are taking over gardens all over the UK. Keep your eyes peeled!
As ever and always, I’d like to stress that truth is subjective. Not one of the surprisingly destructive plants on my list is inherently bad, but they do demand a bit more respect than their labels might suggest. Especially in smaller gardens.
For me, it’s been a lesson in looking beyond the promise of easy coverage or fast results, and thinking more about how a plant behaves long term. I’d far prefer to prioritise native plants that stay manageable, year after year, than cash in on a hot new trend and spend the rest of the season trying to keep on top of it!
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