Q: I want to establish a mulch zone around the base of several young trees. Grass grows right up to the trunks. Can I use Roundup to kill the grass around the base of the trees without hurting them?

A: Yes, in my experience you can spray glyphosate (Roundup) onto plants at the base of a tree if you keep it off the tree root system. The chemical can be absorbed by bark and by roots so be careful to spray it only on the grass. If you are concerned you might hurt the tree, consider using a reduced risk herbicide containing acetic acid like Bioganic Weed & Grass Killer.