Window boxes give a color boost to houses and garden. Use a lightweight potting mix to provide the plants with good drainage and aeration for the roots. Make sure the window box has drainage holes so the roots do not become water-logged. Do not use pebbles or other materials in the bottom of the window box. This just adds more weight to the planter. Remember that the window boxes are heavier when they are watered. They need a strong support system to hold the combined weight of the plants, soil and wood of the box.
Combine 5 to 7 bulbs of each type of spring bulbs to create brilliant splashes of color. Use tulips, narcissus, grape hyacinth, pansies, Greek windflowers, ivy and periwinkle in your spring themed window box. Group each type together to make dramatic color changes. Place your bulbs so close that they touch. Set the taller types of flowers in the back and the shorter ones in front. Pick colors that are compatible with one another.
Plant dwarf zinnias in the corners near the edges of the window box. Place a multicolored Baby Doll pinks in one of the corners. Marigolds go in the center and fill any space at the edge of the window box with sweet alyssum. Let the stems spill over the window box edge. Fill gaps between the flowers with fibrous sphagnum moss.
Plant upright herbs like purple sage, sorrel, tarragon, chives, rosemary or lavender near the back of the window box. Fill in the edges with creeping herbs like oregano or Corsican mint. Edible flowers like johnny jump ups and nasturtiums can give you long draping stems of color. Other herbs to use in your window box are thyme, lemon thyme and creeping savory. Just harvest the sprigs of herbs as you need them for cooking.
Verbena, ivy geraniums and petunias bloom on long streaming stems. Diascia produce pink and coral colored blossoms. Bidens and nasturtiums have yellow and gold blooms. Plant white, rose or yellow African daises for more color options. All of these plant choices have long, dangling flower stems with a draping nature.
A desert theme window box needs fast draining soil. It only needs watering when it is actively growing. Plant a yucca near the center back of the window box. Echeverias and jade plants are planted on either side of the yucca. Place hens and chicks near the front edge where their low growing habit can be shown off.