Garden thugs – the best, the worst and one to avoid!
‘Garden thugs‘ don’t sound like a good idea.
While researching this post, I looked at our own back border. It is literally full of thugs.
For a moment, I thought I might have to dig it all up and start again!
But after talking to multi-award-winning professional growers Rosy Hardy of Hardy’s Cottage Garden Plants, Paul Seaborne of Pelham Plants and Steve Edney & Louise Dowle of the No Name Nursery, it became clear that even the most vigorous plants can be surprisingly valuable in our gardens.
Can you spot the garden thugs here in my garden? Japanese anemone, Lamb’s ears and euphorbia with phlomis and acanthus mollis further along the border out of sight.
What are garden thugs?
Hardy’s Cottage Garden Plants has won 25 Gold medals at RHS Chelsea and more in other shows. Rosy Hardy also has a YouTube channel called Rosy Hardy Gardening and a membership club called Straightforward Gardening with weekly videos on exactly what to do.
She defines thugs as ‘plants with aspirations to take over the world. You plant one plant and suddenly you have an acreage of it.’
Some plants spread because they self-seed enthusiastically.
Others run underground with roots or rhizomes, popping up several feet away from where you planted them.
A third category are ‘runners’ travelling over the earth with stolons (like some lawn grasses). These can be the easiest to pull up.
However, these are the plants that will grow where other plants won’t. They help suppress weeds (even the weeds can’t compete!).
And they save money because even if you buy or are given a tiny piece of root, you will find yourself with several dozen plants, creating a striking presence and a blaze of colour, within a year or two.
Three types of garden thugs: self-seeders which scatter themselves around, plants which spread underground via roots and rhizomes and plants which ‘run’ over the earth, such as comfrey. Runners are easy to pull up – so they make some of the best thugs.
Anne Wareham and Charles Hawes’ garden Veddw has been ranked one of the top 100 British gardens. Anne says she relies on ‘garden thugs’ to keep it low maintenance.
See Veddw in The Low Maintenance Garden That Still Looks Fabulous.
Which plants will take over your garden?
Paul Seaborne’s Pelham Plants nursery has won Gold medals at RHS Chelsea, too. He also co-ordinates the Plant Fairs Roadshow, a collective on independent nurseries and specialist growers who sell plants at fairs throughout the South of the UK.
See this post for planting tips and plant recommendations from the Plant Fairs Roadshow growers.
Paul specialises in perennials and ornamental grasses. He defines a garden thug as ‘a plant you’ve lost control of.’
Plants that are most likely to be thugs include:
- Japanese anemones
- Comfrey (running forms of symphytum)
- Many euphorbias
- Bamboo
- Lysimachia ‘Firecracker’
- Plume poppy (Macleaya cordata)
- Acanthus mollis. Some varieties, such as ‘Rue Ledan’ are less likely to take over your garden.
My garden is full of thugs – but I particularly love Acanthus mollis Rue Ledan, which is much less aggressive than the purple-tinged acanthus mollis.
Are garden thugs always a bad idea?
Not necessarily.
Rosy Hardy keeps vigorous symphytum at the back of her garden because:
‘I want the nettles (for caterpillars).’ But she doesn’t want them to spread out of control.
The symphytum suppresses weeds and offers benefits to pollinators while keeping the nettles from spreading. still leaving enough nettles for caterpillars and pollinators.
Paul Seaborne loves the statuesque flowers of plume poppy (Macleaya cordata) even though he warns customers how vigorous it is:
‘It dominates, but it’s held in by lawns and hedges.’
The key message from all three growers is that context matters. A vigorous plant may be useful in the right place but a mistake in the wrong one.
Paul Seaborne keeps Plume Poppy (Macleaya cordata) under control because it is surrounded by either lawn or hedging.
Which plant did the experts say we probably shouldn’t grow anymore?
Rosy Hardy is particularly cautious about bamboo.
‘People just really shouldn’t be putting bamboos in their garden anymore.’
Paul Seaborne also warns that some bamboo varieties can travel under lawns and across pathways before suddenly appearing elsewhere in the garden.
Steve and Lou grow bamboo in their own garden and think it works well in an urban garden for privacy and noise reduction.
But even they say that you have to take steps to stop it spreading.
The best way to grow bamboo is probably in a container. Some bamboos can spread even if you try to restrict them with membranes or other barriers.
When does a fast-growing plant become a problem?
Paul Seaborne says the answer is observation.
‘You need to observe your successes and your failures.’
Take a cup of tea or a notebook out into the garden. Or even just observe how plants are growing and interacting while you’re watering or weeding.
If a plant starts dominating weaker neighbours, shading other plants or appearing in unwanted places, it’s time to intervene.
He also points out that early action matters: ‘If you catch a potential thug early and the roots aren’t too deep, it’s dead easy to deal with.’
What’s the difference between a garden thug and a good doer?
Steve Edney and Louise Dowle from the No Name Nursery say that almost any plant can become a thug in ideal conditions.
A good doer is different:
- it grows strongly without aggressively spreading sideways
- it forms reliable clumps over a longer time than thugs do
- it survives well in ordinary conditions
- it doesn’t usually regrow from tiny root fragments left in the soil
- it mixes well with neighbouring plants
Paul Seaborne adds that a good doer should have:
- a long season of interest
- resilience
- the ability to coexist with other plants rather than dominate them
Which plants are the best good doers?
Plants recommended by the growers as reliable good doers include:
- Geums
- Hardy geraniums
- Astrantias
- Honesty
- Erigeron karvinskianus
- Ajuga reptans cultivars
- Lamium maculatum
Rosy Hardy particularly recommends geums because:
‘They repeat bloom really well’ and ‘the early flowering ones have wonderful seed heads.’
Paul Seaborne recommends honesty for its exceptionally long season:
- seedlings appear in winter
- flowers emerge in spring
- seedpods develop through summer
- dried seedheads last into autumn
Geums are Rosy Hardy’s favourite good doers, along with astrantia and hardy geraniums.
What are the best ground cover plants to suppress weeds?
Rosy Hardy recommends:
- Carpet bugle (Ajuga reptans)
- Dead-nettle (Lamium maculatum is best). Note that Yellow Archangel (Lamium galeobdolon) is an invasive dead nettle in the UK so avoid that one.
- Comfrey (symphytum)
She says ajugas and lamiums spread effectively but are still relatively easy to dig out and control because they are shallow rooted.
I use comfrey myself in a patch where ground elder had got out of control.
We suppressed the ground elder with a black horticultural fabric for a season, then planted the comfrey. The ground elder can’t compete and the comfrey is easier to dig up than the ground elder was because of the shallow roots.
It was a very cheap way of planting up the area because I got several square feet of comfrey from just a few roots given to me by a friend.
There are some brilliant ground cover plants – which include thugs and good doers – in 23 Ground Cover Plants for A Tapestry of Colour in Difficult Places.
Are self-seeding plants a good idea?
All three growers were positive about self-seeders. They’re plants for free.
But they are potential thugs if you let them. I planted Smyrnium perfoliatum in my borders twenty years ago. For the first 15 years, I tidied away the seedheads so I was able to enjoy the ones that did self-seed.
Then I started leaving them. This year we had smyrnium everywhere. In paths, in the cracks of pavers, all through the lawn and in every border. It meant a couple of months of intensive weeding, but the battle needs to be won.
There is a case for leaving seedheads, but not if plants are invasive or very aggressive. See The 20 Best Plants for Seedheads – Beauty, Wildlife and Less Work in the Garden.
Paul Seaborne says self-seeding plants often ‘position themselves in the garden in a much better place than we ever considered putting them. They fill gaps naturally.
He particularly recommends Erigeron karvinskianus, which naturally appears in paving cracks and crevices without becoming invasive.
See 25 Best Self-seeding Plants to Save You Time and Money.
How do you control fast-spreading plants?
The experts all agreed on a few key principles:
Use physical barriers
Lawns, hedges and pathways can help contain vigorous plants. If a plant pops up in a lawn, you’re likely to mow it down, which will stop most plants from spreading, explains Paul.
Paths create a barrier because it’s so easy to see seedlings popping up. You can take them out easily when they’re young. And the roots of hedges can also out-compete many – but not all – garden thugs.
The roots of hedges and the shadow of their foliage make it difficult for plants to ‘cross’ their barrier. But some plants will! Both Rosy and Paul mentioned bamboo in this context.
Deal with problems early
Young seedlings and shallow-rooted spreaders are much easier to control. Weed them out as soon as you see them. It’s easy when they’re young
Plant it in the right place – don’t move it around the garden
If you’re planting a potential thug, then think carefully about where you’re going to plant it, advises Steve. If you decide it’s the wrong place and try to move it, bits of roots will get left behind. These will quickly sprout into a thuggish clump.
Observe your garden regularly
Paul Seaborne says even a quiet cup of tea while walking around the garden counts as gardening. While you’re watering, hoeing or weeding, assess your plants. Is one clump getting too big for its boots? Is a plant overshadowing another plant?
Paul also advises gardeners to ask questions before buying: ‘If the plant label says ‘vigorous’, that could be code for thuggish.’
Important questions include:
- Is it clump-forming or running?
- Does it self-seed heavily?
- How can it be controlled?
- Is it suitable for your soil and conditions?
But don’t think you’ve got to avoid garden thugs altogether
Rosy, Paul, Steve and Lou all think there is a place for thugs in a garden, provided you know what you’re in for.
And all plants need care, adds Steve. You can’t expect to plant a plant, then just leave it for years. It’ll either struggle to survive or completely take over.
Many vigorous plants are:
- tough
- weed-suppressing
- pollinator-friendly
- adaptable
- useful in difficult areas
The real issue is not whether a plant is vigorous, but whether you understand how it behaves.
As Steve puts it: ‘Plants are living things… they’ll move where they want to go, they’ll increase in size and they’ll be having a jolly good time in your garden.’
Pin to remember garden thugs and good doers
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