Herbicides are a big help when you're battling invasive plants, but they must be kept from coming into contact with flowers, shrubs, trees, or grasses. Here's how to make an herbicide work for you. Protect nearby plants. Spread plastic sheeting over large shrubs, grass, or ground covers. You can use cardboard boxes to cover smaller plants. Or cut the top and bottom from a plastic milk jug, and slip the remaining portion over a problem plant before you spray it with an herbicide. Direct the spray into the milk jug to keep it contained.
Always wait for warm, still weather with no rain forecast in the next day to spray. When mixing small batches of herbicide from concentrate, make it in a spray bottle and use the spray bottle only for herbicides. Spot treat in tight places. For best results, mix a small amount of herbicide or pour the prepared solution into a clean container. Add a few drops of dishwashing liquid to help the mixture adhere to the leaves. Use a small paintbrush or sponge to dab it directly onto the plants you want to kill.