The name Himalayan balsam sounds at once exotic and fragrant. But it's actually an aggressive invasive plant that has established itself in Midcoast Maine. Unlike some other invasive species in the state, in can be managed with just a little elbow grease — and some healthy persistence.
And I know this, in part, because I've been wrestling with a proliferation of the plant in my own backyard.
Over the past decade, I'd noticed the growing presence of hollow stemmed weeds with pink flowers that first appeared far out back, down near the river behind my property. Each summer they crept closer to the house, overwhelming rose bushes and flower gardens. Now they grow anywhere that isn't regularly mowed.
Based on photos I'd seen online, it looked like Himalayan balsam. But I needed confirmation, so I brought in an expert.
Rebecca Jacobs is a program manager with the Knox-Lincoln Soil and Water Conservation District, who knows an invasive species when she sees one. She's barely out of her car when she spies a tree that I had planted a decade ago in my front yard.
"This particular one is known as the Crimson King, so it has the purple leaves all year round but that is impacting our native maple population so this is an invasive species as well," Jacobs says.
But what I've asked her to investigate is in the backyard. And as we proceed around the side of the house she easily spots and IDs the suspect: ornamental jewelweed aka "Kiss Me On The Mountain" aka Himalayan balsam.
"Which, botanically speaking, is impatiens glandulifera," says Jacobs. "It hails from Nepal, Pakistan and India, and it came first into Europe to Kew Gardens as an ornamental. Happened to get a little out of hand in Europe and has since crossed the pond and landed here in the United States as well, and was unfortunately first identified here in Knox County. So this is its kind of home base in Maine."
Jacobs pulls a plant out of the ground, noting that it's 6-9 feet tall but has a root mass that's only 4-8 inches wide, making it relatively easy to pull compared to some other problematic invasive species.
The petals are pink or purple, and sometimes white. And at this time of the year, clusters of capsules emerge from the top of the plant — and if you touch one, seeds shoot out in all directions.
Which is why they are also sometimes referred to as "touch-me-nots." To defuse that mechanism, Jacobs gingerly detaches the seed capsules.
"What I normally do in this case is cover the seed capsules with a plastic bag and bend the plant over and snap the top off so that we don't release the seeds," Jacobs says.
The other way to eradicate Himalayan balsam, Jacobs says, is to simply pull it out of the ground. She recommends doing that before the seeds emerge in July. Left unchecked, Jacobs says Himalayan balsam will outcompete other plants for the attention of pollinators. And it will also grow 6-9 feet in a single season, blocking the sun from native plants such as my beleaguered raspberry bushes.
In addition to being easy to manage compared to some other invasives, Himalayan balsam is so far limited mostly to Knox County, and small sections of Lincoln and Waldo counties. And because it's so localized, Jacobs says property owners can play an important role in preventing its spread into other parts of Maine.
Himalayan balsam seeds, by the way, can also catch a ride on shoes, or clothing, so Jacobs says if you do have it on your property, be mindful about not becoming a human vector.
Support for Deep Dive: Invasives is provided by Maine Audubon, Friends of Acadia and Coastal Maine Botanical Gardens.
