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.
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!
Goutweed, Aegopdium podagraria can really take over. I would put it to the top of my list of unwanted, invasive plants.
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.)
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!
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.
Gooseneck Loosestrife, lysimachia clethrodes spreads aggressively.
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.
Creeping Jenny does look nice in container plantings though.
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.
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!
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.
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