Late in July this year, PEI Invasive Species Council member Megan Harris got a call from one of her neighbours in St. Catherine’s. He was convinced he had a rogue giant hogweed plant growing along the edge of his driveway. Megan wasn’t convinced until he said that a previous neighbour was a master horticulturist and had grown giant hogweed in their garden a decade or so ago. Oh great – those darn horticulturists!
So Megan investigated with Council member Beth Hoar and yes indeed it was a giant hogweed plant – a new location for PEI. Since we caught it while it was flowering and before it produced seed we hoped it was a single remnant from an old seed bank left in the soil. That giant hogweed garden next door had long since been taken out. Megan and a visiting botanist cut down the one plant, bagged it and left it to cook in plastic for a week or two before disposing of it (labelled invasive plant) in the black bin for incineration.
But unfortunately the story doesn’t end there. The neighbour mentioned another neighbour had found one in his field the year before and disposed of it. Then his son thought there were a number of plants down in the hollow at the end of the driveway. We investigated with other neighbours. Yes, they were there – most too small to flower this year, but a whole field of them! And then Megan was driving toward New Dominion that same week and no more than two kilometers away saw two more plants in flower in another yard! Could they all be from the same old seed source? It’s quite possible. Seeds of giant hogweed can survive in the soil for several years. If a few plants went undetected and continued to generate seed it is likely these plants are the legacy of that original horticulturist’s garden!
So the moral of the story is this: many invasive plants are beautiful. They’re showy and dramatic and different – all of those traits that gardeners love. But they’re not well-behaved. They don’t stay in the garden where they’re put, and they don’t share space well with other native plants. Please gardeners, before you buy and plant that aggressive non-native plant, have a sober second-thought. Make sure it’s not going to leave the wrong kind of legacy behind in our native woodlands, wetlands or beaches.