12 Flowering Plants for the Summer GardenNick McCullough shares a dozen richly colored plants that will carry your late-season summer garden
Yes, the motto at McCullough’s Landscape & Nursery, our family landscape design and nursery business, is “We love the Midwest,” but we also know the realities of the weather here in central Ohio. Who can forget this past winter with around 10 days below zero? Or the typical summer days in the 90s? After almost 12 years of designing gardens, I’ve learned the hard way what plants I can rely on—not just to survive, but to actually star in the midsummer garden.
After the big glorious blast of spring bloom is over, there’s usually a rough stretch for the garden. When temperatures and humidity start climbing, I count on a dozen tried-and-true, mid- to late-season perennials and biennials that can outperform the “latest Heuchera” or “hottest new Echinacea.”
These classic plants come on strong in midsummer and even last into fall. Some are Midwestern natives particularly well suited to our clay soil and climate, but they will also succeed in most other Zone 5 regions, and other zones as well. Interestingly, several plants—such as Veronicastrum virginicum ‘Fascination’, are American prairie natives that were developed in Europe, then made popular by the naturalistic design movement and such designers as Piet Oudolf and Tom Stuart-Smith.
I think these dozen midsummer classics are ideal for my design style, which I describe as a merging of traditional and contemporary, but the same plants can easily look at home in other garden styles also. I like to plant them in drifts, using big brush strokes—particularly Allium senescens ssp. montanum var. glaucum and Veronicastrum ‘Fascination’. Cirsium rivulare ‘Atropurpureum’ is a stunning accent plant; for containers, I really like Verbena bonariensis and Dahlia ‘Café au Lait’.
Almost all of these make great border plants. My favorite combination: Agastache ‘Blue Fortune’ with blue-violet flower spikes; Rudbeckia maxima with stunning oversized leaves and black-eyed Susan flowers; Veronicastrum ‘Fascination’ with its long tall flower spikes. To my eyes, this is Midwestern midsummer perfection.
1. SNEEZEWEED (Helenium 'Mardi Gras')
This perfectly named cultivar does just as it implies: it adds a party to the garden. It produces a profusion of 2-inch flowers from August to early October, with bright orange petals splashed with yellow. This long-blooming, hot-colored perennial will liven up the dog days of summer. I often use it as an accent to drifts of purple-blue flowers like Agastache ‘Blue Fortune’ (giant hyssop), and the fine texture of a bluegreen grass like Schizachyrium scoparium ‘The Blues’ (little bluestem).
Bloom: Yellow/Red rays (August-October) | Height/Spread: 24-36”/12-18” | Zones: 4-9
2. FIRETAIL FLEECE (Persicaria amplexicaulis 'Firetail')
For a pop of hot color that starts in June and lasts until the first frost, look no further than Persicaria ‘Firetail’. While not aggressive, this sturdy perennial likes a bit of room and will drift and weave amongst a border planting. The bottle brushlike crimson flowers swaying above clumps of dark green lanceolate foliage add a textural dimension to a pond’s edge or in a prairie-style planting like those of Piet Oudolf. It pairs wonderfully with contrasting shaped flowers like Echinacea purpurea (purple coneflower), Ratibida pinnata (gray-head coneflower), or a finely textured grass like Muhlenbergia capillaris (pink muhly).
Bloom: Crimson (June-October) | Height/Spread: 36-48”/36-48” | Zones: 4-8
3. RUSTY FOXGLOVE (Digitalis ferruginea)
This elegant foxglove, redolent with tall, golden spires of tubular flowers, is often used as a free-seeding biennial in prairie style gardens. It makes a big statement in the early summer by gracefully towering over its neighbors. I love pairing it with the native Sporobolus heterolepis (prairie dropseed), Amsonia tabernaemontana (bluestar), and Iris sibirica (Siberian iris). An added bonus: the rusty foxglove is as beautiful in a vase as it is in the garden. It performs best in a partly sunny location in soil that does not go bone dry.
Bloom: Creamy yellow (May-June) | Height/Spread: 36-54”/12-18” | Zones: 4-10
4. GERMAN GARLIC (Allium senescens ssp. montanum var. glaucum)
This compact perennial sports a profusion (up to 30 per plant) of globe-shaped lavender flower heads perched on slender stems. Unfazed by intense heat, it adds a welcome splash of color to the front of the summer border. The narrow, slightly twisted, blue-green leaf blades are also attractive, creating swirling evergreen mounds. Bees, butterflies, and hummingbirds adore the blossoms. As with all Allium, this plant has a faint onion scent, so it’s deer resistant. It will thrive for years if planted in an area with good drainage and full sun.
Bloom: Lavender-pink (July to early fall) | Height/Spread: 6-12”/12” | Zones: 4-8
5. TALL VERBENA (Verbena bonariensis)
I first fell in love with this biennial/perennial, with its slender stems topped with tufts of pink-purple flowers, while visiting Hidcote garden over 12 years ago. It was interplanted there with Anemone tomentosa ‘Robustissima’ (Japanese anemone), and the two tall flowers moved harmoniously in the breeze. From that day forward, I was hooked. It’s also a favorite of all nectar feeders and the seeds attract small birds (especially goldfinches), so plant it where you can observe it during the summer. Caution: It has been known to seed around a bit, and in warmer zones it can be invasive.
Bloom: Rosy lavender (June-frost) | Height/Spread: 36-48”/8-12” | Zones: 7-10
6. LARGE CONEFLOWER (Rudbeckia maxima)
Not your grandmother’s black-eyed Susan, this robust American prairie native is a tour de force in the summer garden. In June and July, the hefty flowers emerge on stems that are nearly 5 to 6 feet, with drooping rays of yellow petals surrounding the very attractive dark brown center cones. The large flower is a favorite of many fauna, such as monarch and swallowtail butterflies, and hummingbirds. Though the flowers are often the focal point, the foliage is nothing to overlook with its powdery blue, tobacco-like leaves. I love pairing this beauty with Achillea ‘Terracotta’.
Bloom: Yellow (August-October) | Height/Spread: 54-72”/36-48” | Zones: 4-9
7. GIANT HYSSOP (Agastache 'Blue Fortune')
Topped with tight bottlebrushes of lavender-blue flowers, giant hyssop is a showstopper. The numerous tiny flowers are packed with intoxicating quantities of nectar and pollen, so this plant is perfect for any gardener who enjoys attracting bees, butterflies, and hummingbirds. I often pair it with dark-leaved plants like Penstemon 'Dark Towers' and Eupatorium 'Chocolate' because their wine-colored foliage complements the blue flowers so well. It's a very easy perennial to grow; both heat and drought tolerant, giant hyssop blooms from spring through summer. The leaves have a pleasant licorice scent and are deer resistant.
Bloom: Lavender-blue (June-September) | Height/Spread: 30-36"/18-24" | Zones: 5-9
8. DAHLIA (Dahlia 'Café au Lait')
'Café au Lait' is a must-have for any dahlia lover. This highly sought after cultivar produces dinner-plate-sized flowers from June until frost. It ranges in color from creamy beige to peachy blush and has become a favorite of florists in recent years. I grow it for cut flowers at my other place in Ohio, Red Twig Farms, and it frequently adorns my dinner table. I love to combine it in a bouquet with Hydrangea paniculata 'Limelight' (panicle hydrangea) and Alcea rosea 'Nigra' (black hollyhock). You can grow it as an annual in cooler zones, or dig tubers in the fall and store it for replanting the following spring.
Bloom: Creamy beige (June-September) | Height/Spread: 36-48"/18-30" | Zones: 4-8
9. SEA HOLLY (Eryngium 'Sapphire Blue')
This sea holly cultivar sparkles in the garden, with starry, teasel-like flower heads in a brilliant steely blue color that continues on the stems and foliage. Like ice crystals, the prickly blooms and leaves project from stiff, branching stalks above spiny basal rosettes. Sea holly is ideal as an architectural focal point and cool complement to hot-colored flowers like Helenium 'Mardi Gras' and Coreopsis. While some sea hollies reseed too vigorously, this one is sterile so is not invasive. They're very tolerant of poor sites, so plant sea holly in well-drained, even sandy, soils in full sun. It will flop over if planted in a too-rich or too-shady location.
Bloom: Steely blue (June-August) | Height/Spread: 24-30”/18-24” | Zones: 5-8
10. BILLY BUTTONS (Craspedia globosa)
Also called drumsticks, this native of Australia and New Zealand can be perennial on the West Coast but is generally replanted every year as an annual in other places. Its low tufts of silvery foliage, a foot tall or so, sport numerous mustardyellow balls of flowers bobbing on thin, 2-foot stalks throughout the summer. A truly tough plant, Billy Buttons tolerates poor, heavy soil and drought. The flowers are beloved by florists and work well in both fresh and dried arrangements. They make a playful, kinetic addition when tucked into a border.
Bloom: Yellow (June-September) | Height/Spread: Foliage 12-18”/6-10”; Bloom 24” | Zones: 3-10
11. GIANT THISTLE (Cirsium rivulare 'Atropurpureum')
Related to the artichoke and cardoon, and not invasive like its cousin the bull thistle, this highly coveted thistle is absolutely stunning. Its deep crimson flowers hover above dramatic, deeply cut, bluish-green foliage on robust, upright stems in July and August. Equally at home along the water's edge or in a prairie-style perennial border, this giant thistle adds an air of whimsy to a garden in need of summer color, and also makes a wonderful cut flower. I like to pair it with a perennial that has smaller, rounded foliage, like Baptisia australis (blue false indigo) for textural contrast. This is a must-have for all the plant nerds out there.
Bloom: Dark crimson (July-September) | Height/Spread: 36-48”/18-24” | Zones: 5-9
12. CULVER’S ROOT (Veronicastrum virginicum 'Fascination')
This is another fine example of an American native that is perfectly at home in the designed garden. Plant this graceful perennial in the border and you will be the envy of the neighborhood. The stalks, which can be up to 5 feet tall, are adorned with candelabras of slender, lilac-colored flower spikes that emerge in July and August. Despite its height, it typically only needs staking if planted in too much shade. It combines well with other natives like Rudbeckia maxima and Deschampsia cespitosa (tufted hair grass).
Bloom: Rosy lilac (July-August) | Height/Spread: 48-54”/18-30”; Bloom 60” | Zones: 3-8