Lilies of the valley grow from full shade to full sun with underground root structures called rhizomes that easily self-propagate. They can fill in space quickly and take over a garden if left on their own. Lilies of the valley are usually dug up and divided to help control their growth. Eradicating them completely is difficult but can be done.
Dig up your lily of the valley rhizomes, which typically grow just below the surface of the soil. Remove as much of the roots as possible. If you leave a little bit behind, they will grow again.
Remove the roots again if your lilies of the valley return. Repeat this process several times to completely eradicate your plants.
Spray glyphosate on the shoots as they emerge. Do not get the herbicide on any other plants. Apply on a day when rain is not forecast. Repeat if new shoots appear.