In a window flower box as shallow as 6 inches, you can grow shallow rooted fruit and vegetable plants. Imagine opening a window from inside your home to collect fresh produce for a meal. Choose a window box with drain holes (or drill holes yourself) that is at least 6 inches wide and 6 inches deep. Install the window box on the sunniest side of the house. In addition to installing flower boxes beneath a window, flower boxes are also suitable on a balcony, patio, fence, deck railing, or directly on the ground. Fill the flower box with fresh potting soil or a 50/50 mix of potting soil and ground soil. Plants seeds or starter plants after the last frost date as indicated on the chart at Dave’s Garden. Either push seeds into the soil about ½ inch or drop seeds and then cover them with soil.
Lettuce
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.
Radish
Radishes 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.
Spinach
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
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.
Pansy
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.
Sources: Container Vegetable Gardening, Ohio State University Extension Factsheet; Home Grown Facts About Pansy, Cornell Cooperative Extension
More garden articles from this writer:
How to Care for Potted Macrophylla Hydrangea
Best Shrubs for Outdoor Containers
Get Rid of White Fuzzy Spots on Zucchini Plant Leaves with Homemade Fungicide
