Creeping bellflower is having a moment in Minnesota yards this summer, and not the kind gardeners want. The invasive plant's purple, bell-shaped blooms look nice enough from the curb, but Laura Irish-Hanson, an extension horticulture educator at the University of Minnesota, says the plant is built to be nearly impossible to fully remove.
The problem starts underground. Creeping bellflower spreads through rhizomes, tough horizontal roots that snap apart the moment someone tries to dig the plant out. 'When you try to dig it, we actually just snap those rhizomes right off,' Irish-Hanson said. 'If we leave any of the root pieces behind it can actually just encourage more branching and more plants to grow.' Pull one plant and you can end up planting several more without meaning to.
Then there's the seed math. A single plant can throw up multiple flowering stalks and produce roughly 150,000 seeds, Irish-Hanson said. She also notes the plant thrives in disturbed urban soil, which helps explain why it's so at home here.
The University of Minnesota's Extension weed guide backs up the grim math with its own control advice: hand-pulling only works on small patches, and only if every root fragment comes out, ideally by digging at least six inches down and around the plant. Herbicides like dicamba and triclopyr help but need repeated fall applications, while glyphosate requires multiple treatments and won't discriminate against surrounding plants. Smothering a patch with a tarp or thick newspaper is another option for garden beds. Maintaining dense, healthy turf remains the best long-term defense in lawns.
In the meantime, Irish-Hanson's practical advice is damage control rather than a cure: snip off the flowers before they go to seed, and if you do pull plants, burn them or bag them tightly rather than tossing them on the compost pile, since surviving seeds and root bits can spread right back out. It's not a fast fix, but it's the difference between managing a patch and watching it take over the block.