My husband, Kevin, and I had already identified the subject as a particularly pernicious weed. But, he was right. We’ll never be rid of it.
Known as Canada thistle, this perennial nuisance spreads primarily through its roots, boring a circuitous path as much as 3 feet deep through the garden and sending up clones every few inches. Its fleshy stem snaps easily at the T-juncture, leaving the main root free to keep snaking along and creating fresh clones. New mother plants are easily propagated from root pieces as short as a few millimeters.
In just a few years, that small patch our friend noticed has radiated octopi-like arms throughout a large portion of the garden.
It’s that healthy and prolific.
We suspect our vegetative nemesis arrived with a load of horse or cow manure, although it may have been a gift from the city the year we availed ourselves of free mulch. (Another bonus from that adventure: Poison ivy. Free comes with a price!)
From the thistles’ home base near the trunk of the centermost grapevine, it’s easy to trace its diagonal paths across numerous raised beds. It pops up in walkways, beside companion plants, next to vegetables. It has even found its way into the tiered strawberry bed. So far, the brick sidewalk has kept it from spreading even farther.
Officially classified by the US Department of Agriculture as an invasive species, Canada thistle has a reputation for crowding out native species and reducing crop and forage yields. It has been running amok since the 1600s, when it is thought to have first been brought to the States from Europe in seed shipments.
On the commercial level, run-of-the mill herbicides aren’t terribly effective. Most farmers resort to more potent concoctions to keep it in check.
Since Kevin and I have eschewed such chemical restraints, and we don’t have access to sheep or goats, which might eat the thistles, we’re left with good-ol’-fashioned hand weeding. Pulling the little buggers as soon as they emerge helps deplete that deep main root of its energy reserves, thereby limiting its spread.
This mechanical method doesn’t get rid of the thistles for good, but it’s the best solution we have.