Invasive plants are those that have been introduced into an environment in which they did not evolve and so usually have no natural enemies to limit their reproduction. Many of these plants have escaped from gardens and landscapes where they were originally cultivated. Purchased at local nurseries, at garden centers and online, these plants have the potential of taking over large areas, affecting native plants and animals and negatively changing local ecosystems.
Joanna, a gardening expert from Gingham Gardens has shared six invasive plants that gardeners may wish they had never planted.
Snow-on-the-mountain or what’s commonly known as bishop’s weed or gout weed is “hands down the worst plant to grow” in gardens, according to the gardening expert.
She said: “I came to hate this stuff. I know hate is a pretty strong emotion when we’re talking about plants, but if you’ve ever tried to eradicate this ‘weed’ from your garden, you know exactly what I mean.
“Snow-on-the-mountain is so invasive and it spreads by underground runners. I worked for probably three gardening seasons eradicating it from my shade garden. Don’t let this beauty fool you.”
Ostrich ferns are visually interesting plants which will thrive under more difficult growing conditions, but they can quickly get out of control.
Joanna explained: “I know ostrich ferns are gorgeous, but I’m warning you they will take over your garden wherever you put them.”
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However, the gardening pro warned: “Don’t be deceived by my charming description. In addition to being invasive, the oils in tansy are highly toxic so be sure to wear gloves when handling it.”
She explained that she once got this in her own garden and the plant had managed to spread into the grass and “encroached on neighboring plants”. Joanna claimed that it was “a pain to get rid of”.
There are many, many varieties of this plant and lots of them are very well-behaved. However, creeping bellflower is not one of them. The expert called it “the thug of a flower garden”.
She said: “I inherited some creeping bellflower with our current home and I cannot get rid of it. I even went so far as to dig up the entire small area where it was growing and by the end of summer, it was back.
“There are other varieties of campanula that are quite aggressive too, so just be careful and do your research before you purchase campanula.”
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Moist and shady locations are where the plant tends to be at its most invasive but it also reseeds itself aggressively in locations with full sunlight.
Lily of the valley
The flowers on Lily-of-the-Valley are so sweet and their fragrance is amazing. However, they can be “very aggressive plants” according to Joanna.
She said: “Lily of the valley bloom for such a short time, that I don’t think they are worth their trouble.
“They are naughty spreaders and do not stay where you put them despite efforts to contain them.”
Once established, lily of the valley is an unstoppable force to be reckoned with. Even if you plant lily of the valley in a contained area, the rhizomes are likely to tunnel under and make a break for freedom.
Common orange lilies
The orange flowers of the common orange daylily can brighten up any outdoor space and many gardeners may have these flowers growing in their garden.
However, the gardening expert warned: “They are prolific spreaders, they crowd out other plants and they are the devil to get out of your gardens.”
Kristi Waterworth at Gardening Know How agreed. She said: “Common orange daylilies, also known as ditch lilies or tiger lilies, are extremely invasive and hard to kill once established, but unlike many garden favourites, these daylilies don’t need special care to get established, or possibly any care whatsoever .
“They may spread from a stand started long ago, or from tubers pulled out of other gardens and tossed on the ground in your garden. Many gardeners find their daylilies are out of control and panic, but pulling them takes patience – these are not your typical landscape plants.”