Cool-season annuals are an excellent choice to balance out and show off your tulips. Choose low-lying flowers that have the same light requirements as tulips do, such as primroses and pansies. Both plants will spread and bloom all spring long if given proper care. Although these flowers won't grow tall enough to hide the dying foliage of the tulips, they will provide a nice, colorful border to any tulip bed.
Other bulb plants can take over blooming where your tulips leave off, and you have to plant them only once, since most will return each year. Try Crocosmia, which is a clumping plant that grows on corms. The tall, slender stems lined with small blooms are a good foil for tulips, and like tulips, they make excellent cut flowers. Hemerocallis, or daylilies, will start blooming as tulips fade and will bloom continuously all summer long. They come in a wide range of colors and sizes.
Foliage plants are a good way to let the blooms of tulips take center stage but still fill up the space with beauty. Hostas are distinctive for their large, broad leaves and are a nice contrast to tulips, which feature much thinner foliage. Carex morrowii is a clumping ornamental grass that presents the opposite effect: The long, slender leaves mimic those of tulips. This plant, however, will stay green long after the tulip leaves have faded.
Geraniums are summer-blooming plants that thrive in the same growing conditions that tulips prefer: full sun and well-draining soil. These flowering beauties come in a large array of shapes, colors and sizes, from trailing plants to large, upright forms. They will begin to bloom a few weeks after tulips have faded. For late-summer color that lasts well into fall, try planting some asters over your tulips. These hardy flowers look like daisies, and many are jewel-toned in the hues of autumn.