Midwest native coneflowers (Echinacea purpurea) bloom throughout the summer. Plants range in height from 16 inches to 4 feet, depending on the variety. One of our favorites, 'Kim's Knee-High', tops out at 16-20 inches, and doesn't flop over in the wind and rain. Traditional colors are pink-purple and white, but new cultivars such as 'Tomato Soup' showcase red, yellow and other bright hues.
Evergreen and tough, Lenten rose (Helleboros orientalis) is a shade-lover that often blooms while the snow is still on the ground. Flowers come in shades of purple, red, near-black, white, green, and pink. Plant it near a walkway so you can enjoy the show in March. Each plant grows about a foot tall and 18 inches across.
Virginia bluebells (Mertensia virginica), a spring flower, sport pink buds that blossom into pink-purple blooms. Happy in sun or shade, each plant grows 2 feet high and wide. Bluebells easily reseed themselves, so a colony can grow larger over the years. Plant Virginia bluebells behind a summer bloomer to hide the foliage that turns brown and fades by June.
The scalloped leaves and pale-pink flowers of Geranium x cantabrigiense are larger than other hardy geraniums. Dense foliage and apple-scented spicy perfume make the plant perfect for borders. Plants, which begin flowering in June, grow about 6 inches high and 14 inches wide. They flourish in full sun and need little water. In the autumn, the foliage turns a dramatic burgundy.
The bright-gold flowers of Black-eyed Susans (Rudbeckia fulgida)stay in bloom more than a month beginning in August. Popular varieties include "Indian Summer" (shown here) and "Goldstrum." The spiky seed heads offer winter interest and bird food. Grow these no-maintenance beauties in full sun, and expect them to reach 3 feet tall and 2 feet wide.
Members of the onion family, alliums (which include chives) are easy to grow from hardy bulbs. Purple allium, with its unique pom-pom shape and leafless stem, brings height to beds of low-growing plants. Lavender Globe Lily and Turkestan Onion varieties thrive in partial shade, making them a natural partner for the shade-loving hosta in our photo.
Cloudlike panicle (H. paniculata) hydrangeas are especially recommended for the Midwest because of their cold tolerance. Because of their large size (6-8 feet tall and wide) and vase shape, these hydrangeas often appear in hedges, borders or as a garden focal point. 'Pinky Winky' panicle hydrangea, shown in our photo, has cone-shape flowers that emerge white and mature to pink.
Sedums are easy to grow, stingy with water, and rich in texture and shape. With its masses of flowers and light gray-green foliage, 'Autumn Joy' (in our photo) is familiar to many Midwest gardeners. By midsummer, it produces green broccolilike buds, which open into large pink flower heads that deepen to rusty red by fall. Other favorite sedums include 'Purple Emperor', 'Vera Jameson' and 'Meteor'.
Creating a wonderful lacy mix of gray and amethyst, Russian sage (Perovskia atriplicifolia) bursts forth in late summer or early autumn, rising 3 to 5 feet tall. It's an excellent companion to plants such as roses, ornamental grasses or tall sedums. As long as it has good drainage, it is extremely low-maintenance.
Though it has the word weed in its common name, don't let that scare you away from butterfly weed (Asclepias tuberosa). Sometimes called milkweed, it's as easy to grow as a weed but much prettier, plus hummingbirds and butterflies (especially monarchs) adore it. Clusters of orange, yellow, pink or vermillion flowers appear in mid- to late summer, followed by thin, ornamental seedpods.
Don't blame your hay fever on goldenrod (Solidago rugosa). (The real culprit is ragweed, which happens to bloom at the same time.) Goldenrod's dramatic fountain of gold erupts in September and lasts into October. One variety we especially like is 'Fireworks,' which grows to 3 feet in full sun. Other varieties reach 2 feet to 4 feet.
After everything else in the garden has quit blooming, the intense amethyst-blue hooded flowers of Azure monkshood (Aconitum carmichaelii) remain intact. The flowers and leathery foliage can even survive a freeze. The sturdy spikes of Monkshood grows 4 to 6 feet tall and bloom in October and November. These plants like partial shade to full sun. One of our favorite varieties is 'Arendsii'.
Click here  to read more about perennials in the Plant Encyclopedia of our sister publication, Better Homes and Gardens.