Window boxes on the shady side of a building provide an ideal place for plants. With no direct sun to overheat the plants and dry out the soil, it is much easier to keep a window box attractive. Select shade loving plants that will develop into lush specimens. Look for colorful foliage as well as flowers.
Coleus (Solenostemon scutellarioides)
Coleus plants, known for their colorful foliage, will grow into excellent window box plants in shady conditions. Coleus foliage is available in a wide variety of color combinations that include shades of green, red, pink and white. Choose from lobed, smooth edged or various lacy edged leaves. Start coleus plants from seeds or rooted cuttings. Pinch back coleus plants to shape them, or allow them to ramble over the edges of a window box.
Calico Plant (Alternanthera sp.)
Choose from the different species of calico plants for your shade window box. These foliage plants are available in red, yellow, pink and orange leaved varieties, and some variegated combinations. Look for the low growing, trailing types for window boxes. They make excellent filler plants, and will cascade over the edges of the box in soft waves.
Tuberous Begonias (B. x tuberhybrida)
Tuberous begonias thrive in shade or partial shade, providing continuous cascades of colorful flowers from early summer until frost. Start the tubers indoors early, about eight weeks before the last expected frost date for your area. Transplant them into a window box when there is no danger of frost. Begonias like moist soil that is not soggy. They may need daily watering.
Impatiens (Impatiens wallerana)
Impatiens provide color in a shady window box as well as lush foliage. The plants can cover a large area, and will gracefully trail over the edges of window boxes. Look for impatiens in shades of red, pink, lavender, orange and white. Some varieties offer variegated foliage as well as colorful flowers. Look for varieties with double flowers that form rosettes, and bi-color flowers.