Home & Garden: Dog-day delights
- Article by: Nancy Rose
- Contributing Writer
- August 19, 2003 - 11:00 PM
Like a cut flower in the hot sun, a garden can start looking limp and washed out come late summer. The spring burst of colorful bulbs is ancient history. The early summer rush of fresh-flowered peonies, iris and delphiniums is just a memory. And the cool fall days that will bring chrysanthemums and asters into autumnal bloom are still to come. So what can perk up the garden through the dog days of summer?
Plenty. There are a surprising number of perennials that come into their own in August, and others can be encouraged to extend their bloom with a little timely pruning.
Native perennials, especially many prairie species, are a rich source of late-summer blooms. Coneflowers -- a common name that's used for several different plant groups -- could fill a garden on their own. One of the best known is orange coneflower (a k a black-eyed Susan or Rudbeckia fulgida). However, orange coneflower can slow down a bit as summer wanes, especially if not deadheaded. But the lesser known sweet black-eyed Susan (Rudbeckia subtomentosa) starts blooming later and is at its peak in the heat of August and early September.
Another overlooked beauty is three-lobed coneflower (Rudbeckia triloba), a bushy biennial or short-lived perennial that is covered with bite-sized blossoms from midsummer until frost. And if you want tall, try the towering (6 to 8 feet) lemon yellow-flowered Autumn Sun coneflower (Rudbeckia nitida 'Herbstsonne').
Other coneflowers include the durable, heat-loving yellow coneflower (Ratibida pinnata), and the ever-popular purple coneflower (Echinacea purpurea). The spiky bronze centers and drooping purple-to-pink petals of purple coneflower make it a winner in gardens and an eye-catcher in bouquets. This showy native also acts as a butterfly magnet when other blossoms have faded.
Options for less sunny spots
While most belated bloomers prefer hot, sunny sites, there are some that do well in moist, shaded areas, too. In August, moisture-loving cardinal flower (Lobelia cardinalis) sends up tall spikes of brilliant red, hummingbird-attracting flowers. Great blue lobelia (Lobelia siphilitica) also loves moist soils and produces many stalks of rich blue flowers from late summer to early fall. False dragonhead (Physostegia virginiana) thrives in moist soil and partial shade, but it also does well in drier, sunnier conditions. The creeping rhizomes of this fuchsia-flowered perennial will spread far and wide if allowed. So try the more restrained, white-flowered 'Miss Manners' if you have limited space.
Yellow flowers predominate among late bloomers such as coneflowers, sunflowers and goldenrods. For a sultry contrast, combine those sunny tones with blues and purples. One of the best for the end-of-summer blues is Russian sage (Perovskia atriplicifolia), a tall, semiwoody perennial that produces masses of tiny lavender-blue flowers from midsummer on. When planted in groups of three or more, Russian sage produces an airy cloud of blue that forms a beautiful backdrop for other flowers.
Other true blue and purple bloomers include balloon flower (Platycodon grandiflorus), ironweed (Vernonia sp.), blazingstar (Liatris sp.) and anise hyssop (Agastache foeniculum). Joe-pye weed (Eupatorium maculatum), a tall perennial for the back of the border, sports plate-sized clusters of tufted pinkish purple flowers in August and September.
Another oversized flower is hardy hibiscus (Hibiscus sp.), which produces huge, tropical-looking flowers nearly a foot in diameter on 3-to 5-foot-tall plants. Many new and improved cultivars of this July-to-September bloomer have come into the market in recent years. Look for pink-flowered 'Fantasia' and 'Sweet Caroline,' red-flowered 'Fireball' and the stunning 'Kopper King,' which boasts white-pink flowers along with rich, copper-colored foliage.
Shrubs add late color
Perennials don't have to stand alone. Annuals and even a few flowering shrubs also bring color to the late-summer garden. Annuals make great filler plants in perennial gardens throughout the summer, but they're especially valuable now. Some annuals that offer color in the dog days include mealycup sage (a k a blue salvia, Salvia farinacea), Texas sage (Salvia coccinea), flowering tobacco (Nicotiana), and tall verbena (Verbena bonariensis).
And don't overlook flowering shrubs when you're looking for some last-minute loveliness. The few shrubs that do bloom at the end of the season can be quite showy on their own or when mixed into the garden.
The large, cone-shaped flower clusters of panicled hydrangeas (Hydrangea paniculata) open white in late summer, then fade to a lovely pink in fall. This large shrub can anchor the back of a garden bed along with tall perennials such as 'Lemon Queen' sunflower and hardy hibiscus.
For moist, shaded sites, the aptly named summersweet (Clethra alnifolia) is a gem. Come late summer, this small-to medium-sized shrub produces short spikes of sweetly fragrant pink or white flowers that mix well with cardinal flower and great blue lobelia.
Potentillas (Potentilla fruticosa) and some shrub roses (Rosa sp.) bloom all summer -- often right up until frost -- and blend beautifully with late-season perennials and annuals. The bright orange hips produced by some shrub roses add extra color as well.
If your garden is looking listless, consider adding some late bloomers. Check out your neighbors' yards, visit public gardens and prowl garden centers to get ideas for your own garden. And remember, early fall is a great time for planting many perennials and shrubs, so you can get a start on improving next summer's garden today.
Nancy Rose is a Twin Cities horticulturist, writer and photographer.
© 2013 Star Tribune