Window boxes add a burst of living colour to small spaces. Typical placement of window boxes would be on the exterior wall of your home under your windows, on the top or side of a deck or along the edge of wooden fences. Fill window boxes with well-draining soil that is rich in organic matter, then mix in a time-release fertiliser before planting. Water your window boxes early every morning to make sure they do not dry out, or put an automatic watering device in each window box.
Bush- or container-type flowering sweet peas (Lathryus odoratus) are ideal for growing in window boxes where their fragrant, colourful blooms are easy to enjoy. These types of sweet peas have a mature height of 6 to 36 inches. Direct sow seeds of sweet peas in window boxes in full sun in early spring. Mulch the top of the soil to keep the roots cool and moist. As temperatures begin to warm up in summer, sweet pea plants begin to die back. Do not pull the plants out of the window boxes; simply cut them off at soil level leaving their nitrogen-fixing roots where they will benefit other plants grown in that soil.
Petunias, especially Wave petunias, are some of the most colourful, popular summer flowering annual plants. An annual plant is one that grows, sets seeds and dies in one growing season. Some varieties of petunias will self-seed and come back the following year. Wave petunias are rapidly spreading plants that will quickly cover the top of a window box and spill down the sides. Wave petunias do not need deadheading to encourage continual flowering like old-fashioned petunias. Deadheading is the removal of faded flower blooms. Wave petunias are heat and drought tolerant. Grow petunias in full sun or part shade.
Pansies are cool-season annual plants with large, colourful flowers in shades of bronze, orange, purple, white, red and black. Pansy flowers have either single or multi-olored blooms. Some varieties have a sweet fragrance that is noticeable from dusk until dawn. They are related to Violas, which are perennials with smaller flowers in shades of purple, yellow and white. Plant pansies in window boxes located in a protected place in full sun in the fall. These plants will flower as long as the temperatures are above freezing during the fall, winter and into the following spring.
Historically, Impatiens were shade plants, but the introduction of the New Guinea Impatiens changed that. New Guinea Impatiens thrives in full sun as long as the soil remains moist. Impatiens flower colours include orange, salmon, pink, red, lavender and violet-blue. Impatiens are trouble-free flowers that bloom nonstop all summer long. The variety of Impatiens that you choose will determine the best place to plant it.