Gardener Beware: Plants That Should Come With a Warning Label!


Not every plant that you find in the garden center or nursery this spring is a good choice for your garden. Garden retailers often sell plants that many consider problematic or invasive.

Why do they sell them then? Well, gardeners often disagree on what constitutes a “problem”. I happen to think that Goutweed is pure evil, but I know at least one friend who thinks it has nice variegated foliage and likes to have it in his garden.

For me a problem plant is not just invasive, it is also one that is hard to remove where unwanted. Aggressive spreaders like Goutweed send out roots that spread underground. Eradicating it is next to impossible. Any of the white root segments that remain in the soil after you remove the surface plant are capable of producing a new plant.

Other plants like the False Lamium (see below) send out runners above the ground that take root and create offshoot plants.The runners shoot off in all directions and it too is hard to get rid of.

To avoid issues with invasive plants, here are a few suggestions:

Generally, it is a good idea to be suspicious of plants with the word “weed” incorporated in their common name. “Goutweed” would be one of them.

Ask nursery or garden centre staff for a reference. If you are considering an unfamiliar plant, ask staff if the plant is in any way aggressive or invasive. Most well-trained staff will warn you off problem plants.

Look up online any uncommon or unfamiliar plants that you are thinking about for your garden. Some plants are fine in one part of the country and a problem in other areas where growing conditions are so favorable that the plant gets easily out of hand.

I am a plant collector and love unusual things, but I have learned not to take chances. If I have any lingering suspicions, I put the new plant in a spot where I can keep an eye on it and restrict it if necessary. Only after it passes a probationary period do I put it out in the main garden.

Do you know a problem plant that we should add to the list? Please share in the comment section.
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

Lily of the Valley! Yes, the flowers are sweet and the fragrance is divine, but it spreads like wild fire. I have it in the back garden in a shady flowerbed under a tree. It can only go so far in this particular bed and is not a concern. On the other hand, it is a huge problem elsewhere. It was in the front garden when we bought the house and spreads by an underground root system. Lily of the Valley crowds my other plants into extinction. Getting rid of Lily of the Valley, where unwanted, has proven to be next to impossible!
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

Goutweed, Aegopdium podagraria can really take over. I would put it to the top of my list of unwanted, invasive plants.
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

The False Lamium 'Variegatum' in my garden isn't my own. It's my neighbour's. Each spring it creeps under our shared fence and then spreads like wildfire through the back of my flowerbeds. I tear it out, but it always comes back the moment my back is turned. Despite its attractive variegated leaves, I've grown to hate it on sight !
False Lamium 'Variegatum' spreads in two ways. It has diminutive yellow flowers that end up dropping little seeds that look like a grains of black pepper.

Even more importantly, the plant sends out runners that settle to the ground and root a few inches or feet away from the mother plant. (Think strawberry plants and you pretty much have it pictured.)
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

Despite my negative feelings about False Lamium, I find myself admiring the pleasing way it spills over the top of plant pots. Just watch that the runners don't take root in the ground under your pot or the flowers don't drop their seeds. Then you might have a problem you didn't see coming!
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

Every time I look at the picture of Gooseneck Loosestrife, lysimachia clethrodes I admire it so much that I begin to think of trying to find a spot where I can contain it. Then I remember how invasive it is and think again.
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

Gooseneck Loosestrife, lysimachia clethrodes spreads aggressively.
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

Creeping Jenny, Lysimachi nummularia which you can see in this Hamilton, Ontario garden is a ground cover that can really take over and is hard to eradicate.
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

Creeping Jenny does look nice in container plantings though.
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

One thing I haven't mentioned so far are prolific self-seeders. Chives are great on potatoes, but they self-seed like crazy! I chop my plants near to the ground after the flowers start to fade to remove any possible seed heads and to rejuvenate the plant.
Other aggressive herbs to watch out for are mint and oregano. Plant them in pots to keep them in check.
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

It is a good idea to deadhead. Not only do you get a fresh round of flowers, you reduce the chances that older flowers will set seed and create new, potentially unwanted plants. This False Sunflower, Heliopsis helianthoides is a great long blooming perennial, but seedlings often show up where I don't want them. I find it really pays to remove the spent flowers!
gardener beware plantings that should come with a warning label, container gardening, flowers, gardening, raised garden beds

This new plant is "on probation" in my garden. Right now it is in a small raised bed. So far it has wandered a bit, but hasn't bolted out of control. I am still waiting one more summer before it consider it safe to plant into the main garden.
Helianthus 'Happy Days' forms an upright mound of pointy dark green leaves and has daisy-like, yellow flowers on strong stems. Height 55-60 cm, Spread 45-60 cm, Care: Average to moist, well-drained soil. My plant is in part shade.
Three Dogs in a Garden

Want more details about this and other DIY projects? Check out my blog post!

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Have a question about this project?

3 of 6 questions
  • Amanda Robinson Greer
    on Jun 8, 2016

    What would be a good ground cover under a tree? It is in the middle of the yard with brick around it (about 8' diameter) but it's a sugar maple so the root system makes it hard to plant anything and is partially above ground. I'd like something that will fill in the area.

  • Nancy
    on Jul 25, 2016

    My worst is chameleon plant ! Not only invasive but stinks when you pull it out! Ever tried it?

    • Chris mara
      on May 21, 2017

      I agree at first chameleon a nice ground cover under my bushes then after a few years it was like wildfire. Every year now I fight to get rid of it - it's a struggle! I am sorry I ever bought and brought it into my yard! Wish I knew how awful and invasive this plant is then. I keep finding it popping up in odd places and wonder if I will ever win the war of eradicating this horrid plant. I too do not want to use poisons as I have an old dog with health issues and grandkids whom I don't want exposed to any awful chemicals!

  • Jean Crabtree
    on Sep 12, 2017

    does anyone know how to get rid of Houttuynia (I call it Hottennanny)-I'm constantly pulling it up --have tried all kinds of spray --even Round Up will not do a thing--Help??????






    • Three Dogs in a Garden
      on Sep 20, 2017

      This is probably not the answer you're looking for. There is no easy way to get rid of this terrible plant. One reason it is difficult to control is that it spreads from underground rhizomes and can root from broken stems and pieces of plants that fall to the ground. This is a plant that can even withstand herbicides (as you have discovered).
      Manually removing the plants and as many of the roots and rhizomes as possible is tons of work, but probably the only way to get rid of it. You may have to repeat this several times to completely get rid of the plants. Once you've dug out as much as you can you can also try covering the area with black plastic. This may slow and help prevent its return. Just be careful that the plant doesn't run under and then beyond the plastic.
      Sorry there is no better way.

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3 of 491 comments
  • Joan Stanley
    on Nov 27, 2017

    Helpful list.
    Sadly 99% of gardening articles are written for cooler and acidic soils than we have in Central and West Texas. I have to keep most of my plants in pots because our soil is alkaline. I would love to have a FLOWERING ground cover for a densily shaded corner of my yard. The area has 6 Live Oak trees with high, invasive roots and thin soil.
    Does anyone have suggestions?

  • LadyD
    on Dec 14, 2017

    JAPANESE KNOTWEED should be added to the list! It looks like a type of bamboo. Has heart shaped leaves, delicate clusters of white flowers that attract bees once a season. Spreads through its underground root system. ANY piece of root that is not removed will sprout into soothe plant. I dug down 3 ft deep in a flower bed between my garage and new blacktop driveway where knotweed had been growing. We poured weed killer and gasoline in the hole and refilled it with sand & dirt. Blacktopped over it and thought that would be the end of it. Several months later I noticed small bumps forming in my new driveway. The bumps raised up and the blacktop started to crack....like small vilcanos forming. It was the Knotweed growing up through the driveway!!!!

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