Ornamental vegetable gardening is not a new idea. Potagers, or decorative kitchen gardens, were a part of the elaborate gardens at Versailles during the reign of Louis XIV in the 1600's. Today, Rosemary Verey, an English author of gardening books, and other famous gardeners still add ornamental interest to their vegetable gardens through the skillful blending of vegetables and herbs with varying textures and colors to create garden tapestries. Potagers are often geometric in layout. They are also often edged with ornamental plants.
Many European gardeners edge their potagers with boxwood.
However, almost any small mounding plant will work as long as it does not hinder the growth and production of the vegetables within. The vegetables should receive full sun at all times or production can be compromised. Try Dalhberg daisies or marigolds for a blooming edge. Potagers tend to be formal in design with pathways dissecting them. Trellises and archways are common features in many decorative kitchen gardens.