Warning: Dog-Strangling Vine about to pop

This may be our last chance this summer to catch a major pest before it spreads its seeds. Watch out for these monsters: Under-ripe pods, packed with feathery, airborne, milkweed-like seeds.

If you’re a Toronto Gardens reader, you’ve noted our campaign against the steamroller known as dog-strangling vine (DSV) or pale swallowwort (Vincetoxicum rossicum, syn. Cynanchum spp., the latter word derived from the Greek meaning “to choke a dog”) Our previous warnings about this highly invasive, non-native twining weed can be found here, here and here.

I’m not the only one calling this a pest. Info from OMAFRA, Ontario’s ministry of agriculture, can be found here. According to a PDF from Canada’s Ministry of Natural Resources (which I wish I could post, but I don’t think blogger will let me), dog-strangling vine arrived in the northeastern United States from Eurasia in the mid-1800s.

In addition to overwhelming large areas of natural habitat, DSV is a threat to the Monarch butterfly, which is attracted to lay eggs on a plant that cannot support the caterpillars.

If you find it in your garden, please do yourself, your neighbours and a lot of pretty butterflies the service of removing it and disposing of the seeds. Cut the main stem off at or just below the soil with a knife or secateurs. Don’t pull on the stems, as this can break the underground root system, which will send up new shoots in other areas. Continue to cut off any new stems as they appear, which should gradually starve the root.

However, do not add the seed pods to your compost heap or composter, as killing them requires much higher temperatures than is likely produced in a home garden. Instead:

• Collect the seed pods in a paper bag, dry them and burn them in a fireplace or outdoor firepit.
• Or, boil them in water, after which they can be safely added to your compost.

This and more information about safe disposal came from this link from the Fletcher Wildlife Garden in Ottawa, which has had experience battling large areas taken over by dog-strangling vine.


  1. Thanks, everyone. I see this weed popping up in people's gardens. Some even leave it to twine around stair rails or other supports. My goal is to get the word out so that they can recognize it as a major problem and nip it in the bud in their own garden. It's certainly a major, major pest in some of the city's wild spaces.

  2. I've been wracking my brain on how to get rid of these things! the more I pulled, the more I got! Now I understand why! Very informative, thank you!

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