Wednesday, June 08, 2011

Thistle Weeds: A thorn in my side

Canada thistle (Cirsium Arvense)This pointy weed might look tough but actually is a delicate plant if you know its weak spots. Thistle is a creeping perennial, meaning the roots will grow like vines under the ground and popup a new plant. It doesn't do well in shade. (

This plant is used to treat: tuberculosis, diarrhea, intestines worms, gastritis, skin eruptions, skin ulcers, and poison-ivy rash (  and The leaves and roots are usually used for teas or mashed up to make a paste. I don't need to tell you that eating a prickly plant is not a good idea.

Killing this weed could be a tough battle. This is one of those plants where you need to attack the greens not the roots. Unless you dig out all of the vine like roots new plants will show up, but this plant is easy to starve out. Every article I read showed that you should take a multi prog approach to remove these weeks (Curt, spray, and shade) They have multiple roots that spider out and can go as deep as 15ft. If digging out the plant is you plan, any roots left behind it will regenerate and create baby weeds (Canada Thistle)Most web pages say not to hand pull the weed, but cut the green part down to the ground.

Chemically Roundup's Ortho Weed B Gone Max seems to be the preferred chemical choice. garden forums says you will need to apply is a second time with the weed comes back. Organically you have lots of options: chop off the leaves, prevent sunlight by covering with cardboard, use farm animals to eat the weeds (like cows), use bugs that love eating this plant (Canada Thistle Stem Weevi), spray with vinegar, or burn with a burn torch.

Personally I will be cutting it down and spraying with vinegar. This might take a few weeks, but slowly starving the plant seems like the best approach. Remember disturbing the roots only encourages new weeds.