How to Plant a Perennial Window Box

Choose perennials that are proportionate to your window box size, focusing on the colors and textures in foliage that best fits your home design and personal taste. Find plants that will be no more than two or three times the size of your container when full grown and match up with sun available to your window boxes. Good design choices include a monochromatic look of multiples of three or five of the same plant or a mixture of plants that include a tall plant, a filler plant and one that trails and spills over the sides.

Mix a small amount of compost or slow-release fertilizer into a high-quality potting soil. Never use garden soil in containers. Potting mixes are created to stay lightweight, noncompacting and nutrient-rich, all while being able to retain moisture while not staying so wet that plants get waterlogged.

Open any unopen drainage holes on all containers involved. Proper drainage is paramount to healthy growth.

Play with the layout by placing your plant choices within the window box to find the design element you like best. There is no right or wrong way. You may wish to allow tall plants to frame windows with fillers and spillers filling in the rest, or you may wish to go a more traditional route of putting tall plants in the center and letting others cascade down from it.

Fill container two thirds full with your potting soil mixture and plant plants as desired. Place soil by hand to finish covering the plants to the crown. Water and place the window box as per instructions, if not already hung.