Leaf lettuce varieties like Red Sails, Salad Bow, Little Gem, and Tom Thumb are good choices for container gardens. Moisten the soil and then plant seeds about 4 inches apart in two parallel rows, with each row close to the long side of the flower box. Lettuce takes about 50 days to mature. Cut off outer leaves as needed, allowing the inner core more growth time.
RadishRadishes grow quickly. Choose varieties like Cherry Belle, Comet, Early Scarlet, or French Breakfast. All mature in less than 28 days. Space seeds about 2 inches apart in two or three parallel rows in moist soil. Poke your finger into the soil next to the growing radish to feel its size. When the radish feels close to 1 inch in diameter, it is time to pull them from the soil. Replant right away to grow more radishes.
Plant any variety, like crinkle-leaf Bloomsdale that matures in about 48 days or plain leaf Giant Nobel that matures in 43 days. Plant seeds 2 to 4 inches apart. Cut leaves as needed or cut the whole mature plant just below soil level.
Strawberries are perennial plants. Purchase overbearing strawberry starter plants, such as Ozark Beauty, which produce two to three crops during the growing season. Set two or three in the flower box. Set the strawberry plant so the crown (that is where the stem meets the roots) is at soil level.
You might not consider pansies as food, but the blooms are edible. Choose red, yellow, blue, white, or bi-colored petals. Plant in spring after danger of frost. Create an opening in the soil the same size and depth as the nursery container. Set plants about 6 inches apart. Spread 1 to 2 inches of mulch around the plants to help retain moisture. The taste of pansy petals is similar to wintergreen. Use the petals to decorate cakes or flavor soups or salads.