Hydrangea shrubs (Hydrangea macrophylla) grow in U.S. Department of Agriculture plant hardiness zones 6 through 10. Grown as a landscape backdrop for its foliage and large ball-shaped clustered flowers, hydrangeas grow up to 6 feet tall, blooming midsummer through fall. Hydrangeas require partial shade in loose well-drained soil with varying pH levels. Bloom colors differ, depending on the pH level of the soil, giving you more control over the garden's color scheme. If the pH level is below 5.5, hydrangea plants produce blue blooms, while pink blooms grow in pH levels above 6.0. Complementary flowers for hydrangeas share the same growing conditions and work well with the hydrangea colors used in your landscaping scheme.
Climbing vines allowed to run along fence lines and arbors or providing privacy grown on a trellis or screen compement the hydrangea garden. Choose vines with pink or blue blossoms to plant near the entrance of the garden with the hydrangeas as a backdrop. The pink or blue blossoms will draw in the colors of the hydrangea blooms from the back of the garden and allow flowers placed in the spaces between to contrast separately. This helps to keep focus on the hydrangea bushes instead of drowning them out with too many flowering colors. Clematis vines are sturdy and come in a variety of colors. The "Nelly Moser" clematis offers pink blooms measuring up to 6 inches and the 8-inch blooms of "William Kennett" are lavender-blue. Both varieties tolerate shade and require light pruning.
Geraniums come in a variety of colors that bloom from late spring until the first frost of fall in USDA zones 9 through 11. Geraniums repel Japanese beetles, a common pest for home gardens. Plant different colors of geraniums around the bottom of the hydrangea bush to bring color to the garden and fill the space between the ground and the hydrangea. Geraniums also work well as borders or planted behind decorative edging. The four basic types of geraniums include the common geranium (Pelargonium X hortorum), regal and angel geraniums (Pelargonium domesticum), scented-leaf geraniums (Pelargonium domesticum), and ivy-leaf geraniums (Pelargonium peltatum). Common geraniums require low maintenance and provide many colors to correlate with the expected colors of the hydrangea blooms, depending on your soil's pH level. Ivy-leaf geraniums grow deep maroon, red or pink blossoms that contrast well with the hydrangea's light-colored blooms.
Ground covers allow you to choose a color to blanket the landscape underneath all the contrasting colors of your flower garden. Light-colored ground covers work well to help the vibrant colors of the flowers to pop out and allow separation between them. Sweet alyssum (Lobularia maritima) and white periwinkle (Vinca minor "Alba") are good ground cover choices in USDA plant hardiness zones 4 through 9.. Sweet alyssum makes a great companion plant to hydrangeas because it attracts hover-flies whose larva feed on aphids, common pests of hydrangeas. It grows up to 12 inches and releases a sweet scent when in full bloom with white, pink and purple blossoms. The white periwinkle is a broadleaf evergreen that grows white star-shaped blossoms, contrasting against the ball-shaped blooms of the hydrangea.
Annual impatiens grow up to 2 feet tall with bright-colored blooms during the summer months. They are native to East Africa and grow best in partial shade. Like hydrangeas, impatiens wilt with prolonged direct sunlight and need moist well-drained soil. They share some of the same growing features of the hydrangea, reducing the need for you to tailor gardening techniques. New Guinea Impatiens (Impatiens hawkeri) have large blossoms in hues close to hydrangea colors, such as pink and lavender, giving you the option of keeping the same color scheme as the hydrangea bushes. Cultivars of this variety include the "Celebration Pink Candy," "Celebration Light Lavender," "Nebulus," "Equinox," "Sunglow" and "Tango." The New Guinea varieties grow best in morning sun and afternoon shade.
- Floridata: Hydrangea Macrophylla
- Michigan State University: Plant Encyclopedia: Hydrangeaceae
- Missouri Botanical Garden: Clematis (Lanuginosa Group) "Nelly Moser"
- University of Hull: Clematis on the Web: Clematis "William Kennett"
- Michigan State University: Plant Encyclopedia: Geraniaceae
- National Garden Bureau: 2012: Year of the Geranium
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