With ornamental grasses becoming more popular every year, gardeners are trying to think of ways to integrate these lovely plants into their gardens. What are the best companion plants for ornamental grasses? Will maiden grass mix with petunias?
First, consider the concept of scale. Grasses come in many sizes, from small mounds of blue fescue to towering plumes of Indian grass. Companion plants should be scaled appropriately. But that doesn't mean you should only plant 6-foot-tall flowers with your 6-foot-tall miscanthus. On the contrary, different heights give the garden a pleasing, layered look. Another concept to consider is balance: Several small plants may be needed to balance one large plant. Don't give in to the temptation to simply plant one of everything.
Also consider the season of bloom. Most ornamental grasses bloom in late summer and fall. Naturally, they look striking paired with fall-blooming flowers. But we want our gardens to look nice throughout the entire season. So try adding some spring-blooming flowers and bulbs. Ornamental grasses can be used to hide the dying foliage of daffodils and tulips.
Plan for a winter landscape. Most grasses look nice throughout winter, until they get buried by a heavy snowfall. Consider adding needled evergreens, weather-resistant garden ornaments, and flowers with attractive seed heads. Think of the winter garden as a gigantic, dried flower arrangement. Small trees like Japanese maples and deciduous shrubs provide year-round structure (referred to as "the bones of the garden"). Some of my favorite shrubs are oakleaf hydrangea, Daphne odorata, redtwig dogwood, 'Crimson Pygmy' barberry, weigela, and shrub roses.
Finally, ornamental grasses look good with each other! Even a small garden has room for several well-placed grasses. You could combine one large Miscanthus with two or three medium-size grasses. Add some colorful flowers, and you'll have a garden that looks like it was designed by a famous landscaper. Aim for different heights, textures and colors.
Now for some flowers to go with the grasses. I've separated these into groups of tall, medium and short flowers to go with different sizes of ornamental grasses, but that doesn't mean you can't mix them up. For example, you can use tall grasses as a backdrop for medium-height grasses and flowers, then place the short ones at the front of the border. Remember to give each plant enough space. You can fill in the gaps with annuals to make the garden look full until the grasses and perennials reach their mature sizes.
Companion Plants for Tall Grasses
These flowers are nice with grasses that grow 5-7 feet tall, like Miscanthus and Feather Reed Grass.
Agastache (Hyssop) -- Blooms in late summer. Attracts hummingbirds. Aster -- Autumn bloomers in shades of pink, purple and blue. Cleome -- Airy pink, purple or white flowers from mid summer to fall. Annual. Cosmos -- A self-sowing annual in a variety of colors. Echinacea (Purple Coneflower) -- A classic companion plant. Eryngium (Sea Holly) -- Wonderful for adding texture. Eupatorium (Joe Pye Weed) -- Impressive, tall perennial with mauve flowers. Gaura -- This perennial makes a great filler. Knautia -- A good filler with a long bloom season. Liatris -- Provides a vertical accent. Lychnis -- Brightly colored flowers are a real standout. Perovskia (Russian Sage) -- Bushy perennial with lavender-blue flowers. Rudbeckia -- Large, daisy-like flowers. Blooms in late summer and fall. Verbena -- Self-sowing, first-year flowering perennials. Solidago (Goldenrod) -- Yellow flowers in late summer.
Companion Plants for Medium-Size Grasses
Try these with grasses that grow 2-4 feet tall like Big Bluestem, Little Bluestem, Pennisetum, Mexican Feather Grass, Northern Sea Oats and Switch Grass.
Coreopsis -- Golden yellow or brick red flowers. Daylilies (Hemerocallis) -- Many colors to choose from. Gaillardia (Indian Blanket) -- For an instant southwestern look. Geum -- Blooms all summer, if deadheaded. Hyssop -- Stunning blue color. Repeat blooms. Lavatera -- A nice annual for filling in the gaps. Penstemon -- Blooms in early summer. Foliage and seed pods are nice in the fall. Platycodon (Balloon Flower) -- White, blue or pink flowers. Salvia -- Perennial or annual species in various colors. Scabiosa -- A nice filler with pincushion-style flowers. Zinnia -- Late summer blooming annuals.
Companion Plants for Short Grasses
These flowers are useful for edging, or for planting in the rock garden, along with grasses that grow 1-2' tall: Blue Fescue, Prairie Dropseed and Sedge.
Viola (Pansy) -- Self-sowing, short-lived perennials.