Lily of the Valley: How Deep does it Go
Dear Master Gardner, We have a 12" strip of dirt the runs between our driveway and the neighbors fence. Once upon a time (roughly 2 decades ago) we planted Lily of the Valley there not knowing how invasive it was. It has even poked holes in our black top driveway. Determined it is! We have dug it out several times, but it has spread to our neighbors yard (they like it) and just when we think its gone, it comes back again under the fence from our neighbors. The lovely Lily of the Valley chokes out everything we have tried to plant in this strip. My last resort is try and put a barrier in the ground that will hopefully stop them from returning once they have been removed again. I am thinking some type of hard plastic should work, but I do not know how deep the roots of this cute but headache inducing plant go. Is there anyone there that knows how deep Lily of the Valley roots go? I have searched on Google but have not found an answer. I would appreciate any assistance in this matter that you can share. I would also be open to any suggestions you may have to discourage furture growth on this plants part. Thank you.
Hennepin County Minnesota horticulture
In a word, glyphosate. Glyphosate (Roundup) will kill anything green and growing. It may take more than one application. I've read edging to 18 inches will keep it in check, but I wouldn't bank on it. I'd use Roundup instead. Here is an interesting reference: