If you have limited space for gardening but still love to grow flowers, one of the easiest -- and most decorative -- ways to do so is in a window box. These boxes fit outside a window sill to give the house a decorative, floral air, but also require plants that can grow in this inevitably sunny location.
Few things indicate spring more strongly than the appearance of early daffodils, in both gardens and flower boxes. These are spring-only flowers that will keep your window box bright and sunny until the later bloomers are ready. Plant daffodil bulbs in bunches, in flower boxes that are heavy enough to support the lush foliage and yellow and white blooms. Use quick-draining soil and bone meal at planting, and plant one daffodil bulb every 12 inches to put up multiple shoots. Give the bulbs four to eight weeks to germinate and start growing, and keep them in full sunshine for a bright blooming season.
Tulips are some of the first spring flowers, and also bloom from bulbs planted the fall before. Isolated in a box, though, many tulips grow year round. Tulips love sunshine and grow in lush, crowded conditions to fill a window box. Plant white, purple, lavender, pink, red, yellow or orange tulip bulbs in quick-draining soil after a short chilling time in the refrigerator. Keep them in full sunlight and give them enough water to keep the soil consistently moist.
The University of Minnesota Extension calls petunias some of the most popular flowering annuals around, with bright lively blooms and a sweet scent. Plant petunias in your flower box for new blooms and fresh fragrance all summer long. Plant large grandiflora petunias or select a smaller cultivar like the compact multiflora or miniature milliflora, and give the plants room for growth and cascading. The University of Minnesota Extension points out that these annuals require full sun all day and do best in quick-draining soil and boxes with drainage holes. Plant petunias in early spring to maintain them through the summer.