Filling the spaces between flowering plants with ornamental grasses, ferns and other foliage plants will pull the aesthetics of your garden together, creating a cohesive look that can continue into fall and even the winter, after blooms have fallen. Doing this can also introduce a variety of greens and textures to your garden. Many foliage plants are also valued because they can usually grow in partial to full shade, where some of the most popular flowering plants won’t thrive.
Some of these plants do like to cover ground, so when considering planting foliage plants, remember that regular upkeep to the edges will be needed to keep them from spreading into your lawn where you don’t want them.
Filling empty or transitional spaces with foliage plants simplifies garden design because you aren't worrying about flower color or bloom time in your choices. You can save those considerations for the highlights and focal points of your garden, instead.
Read about great foliage plants in the download "Foliage Plants," which includes several feature-length articles.