16-07-2025
Ask the Gardener: The bittersweet reality of controlling weeds
Each plant demands a different tactic when hoping to rein in its growth. But before we delve into what to do, we must discuss whether or not eradication or suppression is the most feasible when dealing with weeds. It is tempting to imagine a weed intervention that results in all of the plants going away and never returning, even more so if that intervention did not involve the use of harsh chemicals and without any collateral damage. I have even been known to dream about a Harry Potter-style magic spell that would lift all the weeds out of the ground at once and make them disappear.
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Sadly, no such spell exists, and holding onto the idea that you can get rid of weeds in one fell swoop is a flight of fantasy. Suppression is the best approach, and when combined with competition from desirable plants and timely interventions that leverage our knowledge of weed species, a gardener can hope to keep weeds in check.
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To begin, why are weeds so good at survival? It turns out that they love the disturbance that we create as we garden or as we alter the landscape. Many produce prodigious amounts of seeds that can remain viable in the soil for up to a decade. I am thinking of
The cruel irony is that every time you pull up a garlic mustard, you bring more seeds to the surface for next year. Not letting them go to seed is the first step in suppression. Annual and biennial weeds respond well to this strategy, robbing them of their ability to return by reducing their seed production.
Some perennial species produce aggressive rhizomes that spread underground. Perennial and predominantly woody weeds are a completely different beast altogether.
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One reader writes about his frustrations with one nasty customer,
Q.
I think it's bittersweet — so I hope I'm classifying it correctly — but it's my latest obsession, though it has been for some time, but the last few weeks it has been particularly top of mind as I spend most weekends landscaping my property.
I tore piles out between my house and a neighbor — it felt good to get it out of there. I ripped a thick, attached vine from a massive tree while feeling good about 'saving' the tree. But today, I read that ripping bittersweet out can actually reinforce its regrow, leaving the soil prepared for more invading.
Chemicals seem to be the only thing to really kill them, and with their abilities to regenerate, it's impossible with a two-gallon spray bottle — and no idea if it's safe for kids or wildlife. I feel like it's absolutely everywhere and it has the perseverance to take over vegetation. We live in Chelmsford, but in Haverhill — where my parents live — there's none in their neighborhood, for now.
I know we call them invasive for a reason, but how did it become so prevalent and can we really get rid of it? The town I last worked for put $45,000 toward invasive species on town-owned land, but that will hardly make a dent.
Patrick, Chelmsford
A.
Bittersweet (Celastrus orbiculatus) is one of the worst threats to our fragmented ecosystem and has a long, sordid history of how it became so prevalent in the region. The future holds more challenges, as bittersweet, along with other woody vines such as
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Harvard University botanist
The red berries from Asiatic bittersweet attract birds that spread the invasive weed.
Garry Kessler
The vine produces copious amounts of red berries, which, when eaten by our avian friends, further aid its dispersal. I learned this firsthand as the area directly underneath my winter bird feeder sprouted thickly this spring with bittersweet seedlings.
With large vines entangled in nearby trees, there is an endless supply of seeds to establish and reestablish the vines. If you plant other fruit-bearing trees and shrubs like
For control and suppression, I recommend physical removal of small-diameter stems (up to 1 inch thick). For larger stems, repeated cutting or targeted painting of the freshly cut stem with herbicide is effective. Be sure to use the herbicide judiciously and carefully. Keep children and pets away for at least 24 hours.
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For suppression to be successful in the long term, repeat visits and vigilance are needed. At the municipal level, advocate for more long-term funding to suppress invasive species; short-term injections of funding without follow-up in the subsequent years tend to result in reestablishment.
Ecologically harmful species are an immense challenge, and one can be easily overwhelmed by the scope of it. But do not lose hope! The fight is a noble one and well worth the effort to ensure that future generations enjoy functional ecosystems as well.
Ulrich Lorimer is the director of horticulture at the Native Plant Trust in Framingham. Send your gardening questions, along with your name/initials and hometown, to
for possible publication. Some questions are edited for clarity.