I bought a peony at a neighborhood perennial sale and planted it and now my garden space is full of "quack grass" (?) and it has invaded my iris bed and it looks awful, I have pulled it and pulled it all summer and it just fills up again. Is there any way to get rid of it. I live in Grand Rapids, Michigan.
Quackgrass is a perennial grass that spreads by underground rhizomes. If you try to pull it out, the rhizomes break off and resprout from the pieces left behind. You can try to smother it out by covering with black plastic and mulch or kill it by spraying with a nonselective herbicide such as glyphosate (roundup) when it is actively growing. Either method means killing off everything in the area that the quackgrass has invaded.