Ask a Master Gardener Creeping bellflower is pretty but invasive visitor in garden
Q: I have a problem with a weed that someone told me is wild campanella. It is invading my flower bed. Two clematis have been invaded by the weed and it also is in my peony. The peony had only one bloom this year. The clematis on one side of my house is fine and in full bloom but the two on the south/west side are dying. What can I do to prevent this weed from spreading any further?
A: I think what you have is campanula rapunculoides, also known as creeping bellflower. It’s a common yard and garden invader in our region. It has heart-shaped leaves at the base and forms a stalk with blue, bell-shaped flowers. The flowers are pretty, but the plant can spread aggressively.
If your weed is creeping bellflower, the good news is it’s probably not killing your other plants. Something else is likely causing trouble for your peony and clematis.
The bad news is that it’s hard to get rid of creeping bellflower in a flower bed. To dig it out, you need to dig down about six inches to get its deep root, and you need to dig around it for several inches to get its smaller roots. Any product that would kill the bellflower will also kill your perennials if you spray the area. You can try carefully spot-treating by daubing glyphosate (Roundup) onto the leaves of the plant you’re trying to kill. Follow the directions on the bottle regarding when to apply.
It’s hard to know what’s setting your clematis and peony back without more information. It could be too much water, too little water, soil conditions, powdery mildew, inadequate sun, or other problems.
U of M Extension offers help diagnosing problems at “What’s Wrong with my Plant?” Go to www1.extension.umn.edu/garden/diagnose/plant.