Place pieces of cardboard around your ornamental plants. Keep the cardboard from falling over by placing bricks on either side. It is important when spraying grassy weeds with a herbicide that contains glysophate that you protect surrounding plants. Spray that comes into contact with these plants will kill them.
Wrap a piece of plastic around the bottom of the tree and secure the plastic by taping the top. Lay bricks around the bottom of trees to prevent spray from splashing at the bottom.
Spray your herbicide on a day that is free of wind and rain. Apply the spray by spraying the tops to the bottom of the grassy weeds.
Apply herbicide to weeds that are growing right next to your ornamental plants or grass with a paint brush dipped in the herbicide. Paint the blades of the grass with the herbicide. Remove the plastic from the trees and the cardboard.
Dig up the dead grass after a few days or till the grass into the soil. Replant in the area with your preferred grass, ornamental plants or shrubs to prevent the grass from growing back.