Window boxes spilling over with brightly colored blossoms welcome guests to your home. Coordinate the size and style of the container with the architecture of the home. Contrast the colors of the flowers so they stand out from the color of the building.
Geraniums, perennials in warm climates, are perennial window box favorites as well. The plants have round, ruffled leaves that often have a contrasting band of color. The blossoms are carried on stems from 4 to 6 inches high above the foliage of the bush. From a distance the blossoms look like a round ball of color, but the "ball" is actually made up of 20 or more individual blossoms at the top of the stem. Colors include white, pinks and red. Bushes can grow up to several feet high, but in most cases stay around 12 to 18 inches high and wide.
Geraniums like sunny mornings and shade from the hot afternoon sun. They are somewhat drought-resistant. New geraniums may be propagated from current plants by stem cuttings. Pair geraniums with a cascading plant like lobelia and upright plants like snapdragons for contrast and interest in the window box.
Petunias are annuals. The plants grow to 18 inches high, have nondescript green oval-shaped leaves and when in full bloom are covered with masses of flowers in every color. Flowers are from 1 to 3 inches across, depending upon the variety. The smaller-blossomed hybrids don't have to be dead headed--the spent blossoms removed--to keep on blooming vigorously.
Three petunia plants will fill a 3-foot window box with masses of color in a few weeks. Combine petunias with salvia for height, and verbena with its small flowers and cascading growth habit for contrast.
Miniature roses grow quite well in containers that are 18 inches deep. Roses require rich soil and consistent watering. They don't like their roots hot, so line the window box with sphagnum moss before planting, or plant the roses in a box that fits inside the window box.
Miniature roses grow to 3 feet tall but start blooming when they're 12 inches high. Plant with white alyssum and blue lobelia.
Pansies, daffodils and primroses are a perfect spring combination. Nemesia, English daisies, toadflax and tulips are another spring flower box. Zinnias bordered by marigolds and gazanias reflect the colors of summer. Shade flowers, including impatiens, tuberous begonias, annual begonias and fuchsia, brighten up any window.