While there were several pre-emergent herbicides that provided good control of annual grassy and broadleaf weeds, these herbicides had little if any affect on perennial grassy weeds and the sedges. Fortunately today there are some herbicides that will effectively control perennial grasses such as bermudagrass and sedges in ornamental beds. Before discussing the herbicides for control of bermudagrass and sedges in ornamental beds, we need to discuss proper bed preparation and maintenance of ornamental beds. Weeds usually are a problem because the ornamental beds were constructed improperly or because they are not maintained properly. This means using the proper soil mix for good drainage as well as raising the beds so they can drain better.
Most ornamental plants perform poorly when grown in wet soil conditions.
Also, many of the weeds that occur in ornamental beds such as the sedges are encouraged by soils that stay too wet. Once the plants are established, apply a uniform covering of mulch over the bare ground areas of the beds. This mulch acts much like a dense stand of turfgrass in that it helps prevent light from coming in contact with weed seeds in the soil. Light is a necessary requirement for germination for many of the annual type weeds that occur in ornamental beds. Next, watch the application of irrigation to beds.