How to kill Wisteria roots?

7 years ago

last modified: 7 years ago

In May I cut 10-year old Wisteria "Blue Moon" all the way down to the ground because it was too unwieldy for the arbor where it was planted. Later in the summer my husband became ill and I completely forgot about the Wisteria. Not surprisingly, the roots kept chugging along.

I've dug up as much of the root system as I could. The roots have grown underneath the stone path along the arbor and well into the lawn. There is no way I can dig them all out because these roots are huge. The first photo shows the thickness of the roots that go underneath the lawn. The second one shows how determined they are to spread. I'm sure I've missed many other roots in the area.

We live along a tidal river and don't use harmful chemicals. Is there anything that can be sprayed or painted on the roots to kill this vine over time?

Thanks so much for any advice,

Molie

Featured Answer

NHBabs z4b-5a NH

7 years ago

last modified: 7 years ago

Are you seeing sprouts from the roots, Molie? One way to kill off roots is to simply starve them, but this takes commitment and persistence. You would want to look carefully for sprouting leaves weekly and remove them as low as possible. If you keep up with it so that the wood doesn’t have a chance to harden, you can typically just rub off any new sprouts. Without the energy produced by leaves, the plant will eventually die. Then you can just leave the roots to rot.

Alternately, a disposable paint brush and an admittedly toxic brush killer will do it. For things like this, I use undiluted glyphosate because it breaks down into nontoxic materials in a relatively short amount of time and doesn’t travel in soils or between plants. I make a fresh cut and paint it on the outer edge of the cut surface where the vascular system of the plant (which is just under the bark) will take it to the roots. No need to paint on the center of the cut area since that won’t help. This way I use the absolute minimum of herbicide to the best effect. I know you crossposted this to the organic gardening forum, so I apologize to those folks, but these are your only two options other than continuing to dig up roots. Wonky things like salt will remain in the soil longer and prevent anything from growing where it is spread as well as eventually migrating to groundwater, and herbicides like strong vinegar will kill foliage but not roots.

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Comments (10)

mad_gallica (z5 Eastern NY)
7 years ago
Anything growing in the lawn is easy. Most things cannot handle being regularly cut down to 3 inches, including wisteria. It may take a while, but it will eventually get the idea.
moliep thanked mad_gallica (z5 Eastern NY)
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moliep
Original Author
7 years ago
last modified: 7 years ago
Thanks, NHBabs and mad_gallica for your advice. I’ll be doing this on my own as my husband recovers from open heart surgery.

Yes, I am seeing sprouts from the roots and they are appearing all around this area ... none yet in he lawn but most in the garden soil ... some even in a nearby bed of phlox. I posted photos of the largest root I dug up, but I know there are more.

I was afraid I’d have to resort to some kind of chemical intervention because this plant had an enormous root system that I’m getting too old to dig up. I’ll use the paint brush technique. Do I have to scrape off the outer layer of bark before applying the glyphosate solution?
NHBabs z4b-5a NH
7 years ago
Scraping off outer bark is something I have done, but just around the outer edge of a fresh cut surface also works and is less trouble. With some really stubborn plants like invasive glossy buckthorn I sometimes have to repeat the following year. Now into autumn is a great time to do this.
moliep thanked NHBabs z4b-5a NH
moliep
Original Author
7 years ago
Excellent! I'll start this paint process soon!
partim
6 years ago
My son has a wisteria that is growing in the middle of his lawn, over a pergola. He wants to remove it because it's really in the way. It barely flowers at all. The stem is about 5" in diameter so it's well-established. He is in Waterloo Ontario 5b if that makes any difference. I am concerned that if he just cuts if off at ground level and drills the stump then it will sprout everywhere in his lawn from the roots. Or does that just happen in warmer climates? Or is that not a problem as long as he mows?

I would appreciate any suggestions.
NHBabs z4b-5a NH
6 years ago
Read suggestions above for strategies.
partim
6 years ago
last modified: 6 years ago
Thanks for responding. I read them but still have questions.

He was going to cut the stump very short and then dig around it a bit and hack the stump down so it sits below the surface of the soil, so he can sod over it. But then where does he apply the glyphosate if he's essentially gotten rid of all the trunk and the bark and the phloem under it, and just has roots left? Or is this not a good method and he should leave some trunk?

Also, Is this a good time of year to apply the glyphosate, since the vine has not yet leafed out and is still sending stuff up from the roots to the shoots? Should we wait until it's leafed out and the root system has been somewhat depleted?

We may have trouble getting glyphosate since it isn't readily available in Ontario.
partim
6 years ago
I wondered whether it would work to ring-bark or girdle the vine after it has leafed out.
partim
6 years ago
last modified: 6 years ago
moliep are you still getting shoots?