very tall grasses
I may have foolishly planted some "grasses" that grow at least 10 to 12 feet in summer. Great as a privacy hedge, BUT now they are spreading out into my lawn, rock garden. flower beds. At this point my privacy hedge of arbor vitae have grown enough that I do not need or want the grasses. I do not know the name of them, but I'd like to call them "gone". I tried to cut down to ground level but they sent up new shoots. I cut some off about 3 to 4 inches above ground and tried to drip in some weed killer. More just come. They are green, tall and beautiful but I want them gone. Any ideas?
Allegheny County Pennsylvania
You don't want to use herbicides or dig around near your arborvitae. It's a sensitive plant. Instead, you want to smother the grass by denying it sunlight. To do this, cut it as close to the ground as possible and cover it with damp newspaper or black plastic. Then pile on wood chip mulch.