Lily of valley...very sparse.Pulled all weeds but no improvement-help!

Is it in the shade or sun? It usually prefers shade, if I recall ... or at least, mine did! Lily of the Valley is usually quite invasive so I'm surprised you are having trouble. If your soil is very clay-like, you could try amending it making it more porous and lighter. Try adding a little sand (check what type of sand you need first, though, at a garden centre) or any other substance that will improve your soil.

I don't know Elaine, we dug it all out many years ago and filled the area with sand to have a sandbox for our kids. They are grown up now and have their own families but the lily of the valley is back, despite all the sand we dumped in there. Truly, the only way to get rid of it for sure is a chemical weed killer and keep putting it on until none come back. In our situation, it has grown under the fence to our neighbors yard so I doubt it will ever be gone. You can try vinegar, Epsom salt & soap to see if that will do it. Look up the exact measurements online.

HTH

Please come to my house and pull up all you want. It is as invasive as any weed here in my Iowa yard!

I think the answer is water. At the edge of my hosta bed under some spruce trees, they grow very well and spread. I do water the hosta and it may carry some fertilizer to the LOV also. In a bed near the house that I never water and where a honeysuckle vine died this winter, they have thinned considerably-that group has less plants than when I planted it 6 years ago. Both have about an equal degree of dense shade. I am now trying to remove the LOV out of the hosta bed and into that other section-a constant battle.