Window boxes add charm and a distinctive look to a picture window. They go well with cottage style houses or traditional architecture and can contain flowers that contrast or coordinate with the trim color of the house. A mixed color palette of flowers looks romantic and a one-color scheme adds distinction to the look of the house. Plan the window box arrangement for shade or sun and choose flowers accordingly.
Prepare the Window Box
Well-drained soil in the window box is essential. Cover the window box drainage holes with a piece of broken pottery so the holes do not become plugged. Use potting soil because garden soil compacts and prevents water drainage. To create a homemade potting mix, use equal parts garden soil, sphagnum peat moss and perlite. Fill the box two-thirds with potting mix and begin adding the plants.
Window box arrangements look best when they have tall plants in the back, plants with interesting foliage and plants that hang over the box edge. Choose plants that do well in either sun or shade. For year-long growth, choose both perennials and annuals. The annuals need to be replaced each season as they fade and die. Perennials in a window box need to be fertilized regularly.
Flowers for Sun
Petunia, lobelia, ivy geranium and nasturtiums grow well in the sun. They are also trailing plants and can be used in the front of the window box. Tall plants for the back of the window box are dwarf varieties of delphinium, zinnia, Shasta daisy and bachelor buttons. Coreopsis is a bright yellow flower to add to the middle area of the window box. Dusty Miller has silvery foliage to contrast with the green leaves of other plants.
Flowers for Shade
Impatiens cascade their blooms over the edge of the picture window box. They bloom in a color range of white to purple. Begonias also come in many shapes, colors and varieties and are a good choice for shade boxes. Their waxy green leaves add contrast to other colors in the window box. Columbine planted in the back will grow to 12 inches and grow delicate flowers of pink, lavender, blue or ivory.
Care for the Picture Window Box
Annual flowers such as zinnias and bachelor buttons fade and die after one season's growth. Replace them with new plants each season. Perennials such as coral bells and coreopsis spread each year and the window box will become over-crowded. Divide the plants every three to four years. Fertilize the flower box plants each month and water frequently.