Perennials that complement one another are color-coordinated and feature compatible optimal growth characteristics, such as soil moisture and amount of sunlight. They are also good companions because they have an aesthetically pleasing appearance when planted together. It’s important to conscientiously select perennials that complement one another because these plants live for more than two growing seasons.
1. Cranesbill Geranium and Ornamental Onion
Combining cranesbill geranium “Patricia” (Geranium “Patricia”) and ornamental onion “Millenium” (Allium “Millenium”) offers a deer-resistant, monochromatic, summer-blooming border for a site featuring soil with average moisture and full sun. Growing inU.S. Department of Agriculture plant hardiness zones 4 through 9, “Patricia” comes out first, from early to midsummer, displaying magenta-pink blossoms atop 23- to 29-inch stems. “Millenium” soon follows, from mid- to late summer, with rose-purple flower clusters atop stems 16 to 20 inches tall, growing in USDA zones 5 through 9.
2. Hellbore and Western Wild Ginger
An off-season display of lush foliage and flowers from late winter into spring can grace a partially shaded spot with average to moist soil, such as a woodland garden, with hybrid hellbore “Winter Moonbeam” (Helleborus × ericsmithii “Winter Moonbeam”) and western wild ginger (Asarum caudatum). Evergreen “Winter Moonbeam” puts out large white flowers until midspring on 12- to 14-inch stems in USDA zones 6 through 9 and is considered poisonous, so do not plant them around children's play areas. Western wild ginger, growing in USDA zones 7 through 9, has intriguing triangular rust-brown flowers until early spring and grows 6 to 8 inches tall. Both perennials are rabbit resistant.
3. Joe-Pye Weed and Sweet Coneflower
You can attract butterflies to a site with moist soil from late summer into fall when you plant a border in a contrasting color scheme of Joe-Pye weed “Atropurpureum” (Eupatorium purp. maculatum “Atropurpureum”) surrounded by sweet coneflower “Henry Eilers” (Rudbeckia subtomentosa “Henry Eilers”). “Atropurpureum” produces huge umbrella-shaped flowerheads of small rosy-purple blossoms atop towering stems 82 to 117 inches tall into mid-fall in USDA zones 3 through 9. “Henry Eilers” stands 47 to 70 inches tall, bearing flowers featuring yellow fluted petals encircling a brown eye. It grows in USDA zones 3 through 9.
4. Japanese Painted Fern and Fancy-Leaf Coral Bells
An unusual display featuring red hues and interesting textures is created when you plant Japanese painted fern “Regal Red” (Athyrium niponicum pictum “Regal Red”) with fancy-leaf coral bells “Miracle” (Heuchera “Miracle”). These perennials are the right choice for alpine and rock gardens with average to moist soil or containers in full to partial shade. “Regal Red” puts out silver foliage clinging to red stems 12 to 18 inches tall. Evergreen “Miracle” has green leaves in summer that change to brick-red edged with chartreuse-gold as the weather cools. It grows 8 to 16 inches tall begets pink flowers in mid- to late summer. Both perennials grow in USDA zones 4 through 9.