However, no proven beneficial relationship of this type of interplanting, called companion planting, has been demonstrated under research conditions. Interplanting flowers and herbs among vegetables can add interest to a backyard vegetable garden that often looks too plain. Furthermore, the planting of flowers and herbs in the vegetable garden may attract beneficial insects that will help control pests. To successfully interplant, consider plants with similar nutrient and moisture requirements. A common example is to plant radish and carrot seeds at the same time.
Radishes germinate and grow quickly.
They mark the rows of the carrots that take much longer to germinate and mature. Radishes are harvested as the carrots are just getting established. Leaf lettuce is a good crop to interplant among larger vegetables since it tolerates shade and has few pest problems. Leeks may be planted among sweet potatoes. The sweet potato leaves help shade the developing stem.