I have a large area sectioned off with pavers and have 4 beautiful blue spruce trees, now about 20 ft tall. Unfortunately, there is a ground cover that somehow invaded my garden and I don't know how to get rid of it. This weed/ground cover has a root system that I can't seem to kill. I've pulled them by hand to no avail. Last summer, I tried using the weed wacker to cut it down to the ground. It grew back. I am afraid of Round Up near my spruce. Any ideas?