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Campanula glomerata 'Caroline'?

Thank you! This has stumped so many gardeners. Finally an answer :). Do you have experience with this plant? It seems pretty aggressive, finding its way into other neighboring perennials. Thanks!

Many species of campanula can be aggressive spreaders, glomerata included. Easy enough to rip out if growing where you don't want.

I've been trying to get rid of campanula glomerata for years, as well as creeping bellflower. You can yank it out, but more will replace it.

I have campanula glomerata 'Joan Elliott.' Everywhere. (Well, at least everywhere in the bed where I first introduced it.)

I've tried for years to get it out of the hellebores and catmint, and it continues to grow through both. It even grows through hostas.