Hello Linda

Lily-of-the-valley is often difficult to control in the home landscape, as you have just found!  Plants can be destroyed by thorough, repeated digging and removal of their underground stems or rhizomes. Any pieces of rhizome that are left will sprout  and develop into plants. So sifting the soil may be needed. It often takes two or three attempts to completely destroy lily-of-the-valley by digging. 

Keeping the leaves clipped to the ground will eventually starve the rhizomes, but will take several seasons.

The herbicide glyphosate (Roundup is one brand) is another control option. Lily-of-the-valley is a very tough plant. Look for a product with as high a concentration of glyphosate as you can find- these are usually labeled as “brush killers.” Multiple applications of glyphosate are necessary to completely destroy lily-of-the-valley. If treating with herbicide, be sure to leave the treated leaves on the plant at least for 5-10 days so the herbicide has time to move down to the roots.

Please, always read and follow all label precautions and directions

On Monday, May 17, 2021, 5:00 PM, Ask Extension <<personal data hidden>> wrote:

Glad to help!