Dug them out last year and the root system was crazy, but they're back. What can I use to get rid of them without hurting other plants around them?
How Do I Kill Off Lily of the Valley Flowers?
Certified GKH Gardening Expert
It can be pretty hard to get rid of. Hand digging is about the least damaging to the plants method of control.
You can try cutting the plants off at the soil line and then immediately painting the cut on each plant with undiluted Roundup. The plant will pull the Roundup into the root system and this will help to kill the roots.
Pouring boiling water over the area will also help. But, boiling water is like Roundup in that it will kill any vegetation it comes in contact with.