Cold Climate Gardening

Canada thistle weaves throughout the peony bedObservant readers may have noticed the prickly-leaved weed sidling up to ‘Rozella’ in my last post. That dastardly villain is Canada thistle, aka Cirsium arvense, and it is one nasty customer. According to the University of California Cooperative Extension,

Once established, Canada thistle spreads rapidly by horizontal roots, up to several meters per year. The extensive horizontal root system assures long-term persistence and spread by vegetative means. A segment of root as small as 1/8 to 3/8 inch (3-6 mm) in length and 1/16 inch (1 mm) in diameter is able to propagate a new plant. . . . Once established, Canada thistle is a fierce competitor for nutrients and water needed by crops or native plants. It produces allelopathic chemicals that assist in displacing competing plant species

Okay. It’s obvious this mess didn’t happen overnight. This peony bed was created in 2002, and my weeding practices have been, at best, inconsistent over the years.

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Isn’t this a stunning specimen of Polygonum cuspidatum? The generous rainfall we’ve had this season has brought it into top form. Too bad it’s on America’s Most Wanted list. Yes, this is Japanese knotweed, aka Japanese bamboo, Mexican bamboo, fleeceflower, and Fallopia japonica. (I’ve been told that it’s also known as privy weed, but I couldn’t find any confirmation of this on the web. However, the luxurious stand pictured above is growing right where I was told the outhouse was located, back in the days when our house lacked indoor plumbing. Presumably the leaves were used as a makeshift toilet paper.) And all this luxuriant vegetation will be knocked down by the first frost, only to rise again next spring. Vigorous scarcely begins to describe this ambitious plant. It is invasive. It is beautiful. Who said villains are always ugly? And if you like to play with fire, Plant Delights Nursery sells three Polygonum cuspidatums that they claim do not spread by rhizomes. Two of them are variegated, and they are wow! plants. But will I buy one? Let’s just say, “once burned, twice shy.”

A lot of the weeds are looking really good.

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Last Saturday and this one I weeded the patio bed, each time just enough to get one of my potted plants into the ground. Last week it was Molinia caerulea ‘Variegata,’ and today it was Polemonium caeruleum ‘Brise d’Anjou.’ Both of these have yellow variegation in the foliage which I intend to complement the flowers of the Lady’s Mantle (Alchemilla mollis) already there.

Anyway, as I was weeding last week, several thoughts popped into my head in the form of riddles:

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