Sunday, May 8, 2011

Festival of the Invasives, Japanese Knotweed (oil on canvas, 5 x 7 in.)

6 May finds me sitting by the north west wall of my little red "Pipers House" in Bishops Mills, where the  candy-pink banded spring shoots of Japanese Knotweed are exploding through the moss-covered knobs that are the junctions of taproots and rhizomes.

The Rhubarb got away from me this spring without being painted as emerging shoots. Now I'm waiting impatiently for Asparagus, which is still sleeping underground -  but the Knotweed is showing itself instead, poking up pinkly in festive-looking, thumb-thick shoots about the dry, thin-walled tubes of last year's stems.

The Japanese Knotweed has been here long before we moved into Bishops Mills in 1978. When we had Goats it was their favorite food, diverting them from raiding the garden, but in recent years the patches have expanded.  Since he put up our Knotweed page, Fred has had lots of inquiries about control, so this year we're going to try to suppress this vigorous invasive alien at our place once and for all!

Yesterday we began to pull the Knotweed roots.  Fred began beside "Weirs House", snapping the succulent shoots off into a bucket to take to our neighbours' goats for a special spring treat, and I started in on the patch that makes a tall shady thicket outside the kitchen window of Pipers House - but soon I fell to admiring the vivid contrast between the fleshy pink shoots and the gleaming green moss. Then I began to look for compositions in spite of despairing the lack of time for a painting.

But today Fred suggested that I should paint the knotweed shoots anyway, so here I am in the late afternoon, sitting on my paint caddy and looking down at one of the mossier clumps right next to the house wall, my brushes stuck into the soft damp soil and my palette on my lap, the fingers of my left hand tucked behind the wooden stretcher of a small canvas. Clouds are moving in on our sunny afternoon and the Robins are beginning to sing.

This original painting is available for $275. For information on purchase and shipping, please contact me at


  1. Our Knotweed page was put up to solicit distribution records, but many of the records include pleas for help at controlling the reported stand If you're trying to eliminate a small stand, I think the thing to do is to repeatedly cut the stems to weaken the roots, and then, depending on the situation, place a piece of old carpet weighted down with rocks or slabs over the site, or smooth out the surface of the ground and add the former stand to the area that's mowed as a lawn. The repeated production of shoots weakens the roots and actually shrinks them, so that it can be possible to pull big chunks of the root system out of the ground when the soil is moist. For a stand less than a metre in diameter, you might (after repeated cutting) dig it up with shovels, and set it aside to thoroughly dry and die.
    Any programme of removing Knotweed will take a few years, but if the site is incorporated in the lawn (and all stray sprouts off the lawn are pulled as soon as they're noticed) you won't have to do anything special to control the Knotweed, and as grass gets established it will compete with the remaining Knotweed for nutrients and light. We're cutting all of ours this year, and pushing the harvest through the neighbours Goats, and we've gotten the diameter of the stems in the stands around our houses down to a couple of mm from the standard "inch and a half." Producing all these replacement stems weakens the roots, which are accordingly easier to pull, but they're amazingly persistent. One reads that a carpet mulch has to be left in place for a few years to completely exterminate a stand. The problem is the rhizomes spreading out from the main plant, and I guess all you can do about them is to weed them out, if in garden beds, or mow them, if in a lawn.

    We were just at Plaisance Park, where they're trying to eliminate a 600m stand along both sides of one of their roads, which makes some of our problems seem relatively minor.


  2. After another month of mowing pulling shoots in this stand, the diameter of the many fewer shoots were seeing as we approach fall is down to 1 mm. Not much Grass has moved into the the cleared area, and I guess the next step will be to plant some lawngrass seed.

  3. Grass seed has now been planted on the site of the painting. A scheme of having Squash vines shade out the cut-down stands this summer wasn't as effective as it might have been, because the Squash didn't thrive as well in a dry summer as they might have in a wetter year, but both stands were seriously weakened, and we'll see what spring may bring.

  4. Spring has brought many 1-3mm stems and some larger ones, that had lept up towards a metre in height before I took them out. Control is continuing, and the area will be mowed with the rest of the lawn this year.

  5. ...oops, with us away for the summers, even harvesting for Goats hasn't beaten the Knotweed back, and it's sparsely growing in a wide area behind each of the houses: but at least we don't have any dense stands.


What do you think of this painting, and what do you know about the subject that I have painted?