Window boxes add a boost of color and charm to the home, and give apartment dwellers a chance to experience the pleasure of gardening. Enjoy a succession of blooms by planting flowers in their season. Begin with fresh spring flowers followed by summer mainstays, and finish the season with fall flowers that bloom until frost. Annual flowers are ideal because of their long bloom seasons, and low maintenance requirements.
Spring Flowers - Sweet peas come in both trailing types with vines up to 6 feet long and bush types that grow as much as 2 feet tall. Geraniums are classic window box flowers that grow 1 to 3 feet tall with red, pink or salmon-colored blossoms. Purple shamrocks are grown more for their foliage than their pink or white flowers. Fuchsias produce 2- to 3-foot trailing stems loaded with complicated flowers in combinations of white, pink, purple and coral.
Early and Mid-Summer Flowers - Bacopa grows only 3 to 6 inches tall. This trailing plant has small, fine-textured flowers and foliage that extend over the edges of window boxes. Petunias come in upright, bushy types or trailing types that tumble over the edges of the window box. With hundreds of cultivars to choose from, you'll find a wide range of colors and sizes. Sweet alyssum is a low-growing, trailing plant with honey-scented flowers in white and shades of pink and purple. Heliotrophe produces sweetly scented flowers in shades of lavender and purple on plants that grow 1 to 3 feet tall.
Late Summer and Fall Flowers - Dwarf sunflowers grow 1 to 3 feet tall with flowers ranging from 3 to 5 inches in diameter. Creeping zinnias produce masses of tiny gold flowers on plants that grow 6 inches tall and spread at least 2 feet. Portulaca, sometimes called moss rose, grows 6 to 9 inches tall with twice the spread. Flowers bloom in a wide range of colors and both single and double types. Cypress vine produce vines up to 10 feet long with airy, fern-like foliage and bright red flowers.
Long-Season Flowers - While many gardeners enjoy a constantly changing window box garden, others want to plant once and enjoy it throughout the seasons. Several flowers offer blooms from spring until frost. Impatiens are window box mainstays with nonstop flowers in a wide range of colors. Annual vincas bloom in white and shades of pink and purple. They tolerate heat and dry soil, which is an advantage if your window box sits where it will absorb heat reflected from the glass. Fan flowers produce white or blue blossoms on long, trailing stems. Pansies and violas like cool weather. In mild climates they bloom from fall until they are killed back by spring and summer heat.