Windows are the perfect spot for flower-filled window boxes. Filled with bright blooms and lush foliage, dressing up the window helps enhance the overall look of the home. Whether the window is small or large, often the best flowers are those that grow well in containers and have a mounding or cascading form to spill around the window.
Geraniums (Pelargonium x hortorum) are an annual flower that makes an attractive late spring to early fall window plant. They grow 12 to 24 inches and have a spread of 12 inches. Their clusters of bright blooms come in a range of colors including, pink, red, white and bicolor. Geraniums have an upright, mounding form that makes them an ideal flower for a window box. They grow best in full sun and well-drained soils. You can grow them in all areas as an annual.
Verbena (Verbena speciosa) is an annual flower in most areas, and grows year-round in USDA zones 10 to 11. It grows 1 to 3 feet tall and 3 to 6 feet wide and has masses of cascading blooms that are lovely framing a window. The clusters of purple blossoms on verbena emerge in spring and last until frost, creating a long-lasting window flower. The deep green, dissected foliage on verbena has a billowing, trailing form that helps to create the spreading growth habit. Verbena is both drought and frost tolerant and make for a hardy window flower. They grow best in full sun and well-drained soil.
Serbian bellflower (Campanula poscharskyana) is a perennial flower that has a spreading growth habit and moderate growth rate. It grows 6 to 12 inches tall and has a spread of 1 to 3 feet wide. The masses of 1-inch-wide, lavender blue, star-shaped flowers bloom from late spring to early fall. The evergreen foliage on Serbian bellflowers retains its color in mild winters for a source of vibrancy to a winter window. It grows best in full sun to part shade and well-drained soil. Plant Serbian bellflowers in USDA zones 3 to 9.
Candytuft (Iberia sempervirens) is an herbaceous perennial flower that grows best in USDA zones 3 to 9. It grows 9 to 18 inches tall and looks stunning tucked along a window box. The mounds of white clustering blooms helps to create a full and lush look to the window. They grow best in full sun and well-drained soil that is alkaline.