Rose of Sharon (Hibiscus syriacus)
This exotic beauty thrives in moderate climates. Its tropical-looking pink, lavender, or white funnel-shaped blossoms revive any faltering midsummer garden. At full height, the Rose of Sharon is V-shape. But be warned: This beauty can be invasive, shedding seed capsules that spur weedy seedlings. Remove the capsules before they mature or look for sterile hybrid varieties, such as lavender ‘Minerva’, dark pink ‘Aphrodite ‘, or pure white ‘ Diana’. Mulch well in cooler winter regions. In winter or early spring, cut away last season’s growth (for bigger blossoms).
Growth: 10 to 15 feet tall
Conditions: full sun to partial shade and moist, well-drained soil that’s neutral to slightly alkaline
Zardy: Zones 5 to 9
SHRUB ROSE (Rosa spp.)
No summer garden is complete without roses and thank goodness that not all roses are finicky plants needing high maintenance. Shrub roses are a class of hybrid roses created by the American Rose Society to include plants with a large and bushy growth habit that eluded other categories.
Informal, modern shrub roses offer beautiful blooms all summer and autumn on disease-resistant, easy-growing plants. Flower color ranges in shades of pink, red, white, and yellow.
Almost without exception, shrub roses are tough, winter-hardy plants that can tolerate neglect and poor growing conditions. Use shrub roses as landscape plants, mass plantings, hedges, ground covers, or borders. ‘Alchymist’ and ‘Constance Spry’ are good examples but don’t miss the Knockout series showy shrub roses that bloom in clusters all summer, usually followed by showy hips.
Growth: to 6 feet tall and wide Conditions: full sun and well-drained soil
Zardy: Zones 3 to 9, depending on type
SMOKE BUSH (Cotinus coggygria)
Save some space: This one’s spectacular. In summer, its puffy, pink-to-purple plumes are as eye-catching as cotton candy. In fall, its dark purple leaves turn shades of yellow, orange, and red to create new drama.
The plumes aren’t exactly flowers. The small, rather inconspicuous flowers are yellow-green and grow in groups 6 to 8 inches long; most of them remain unfertilized and grow hairs that appear as smoke. Highly drought tolerant, it needs little pruning, except to keep it small.
Growth: 12 to 15 feet tall
Conditions: full sun and any well-drained soil
Zardy: Zones 5 to 8
SpIREA (Spiraea japonica)
Easy-to-grow, summer-flowering spirea spreads slender branches into fans of dark green foliage with clusters of raspberry-rose flowers that are attractive to butterflies. If deadheaded, the bloom continues into September, sometimes followed by red or orange fall leaf color. Varieties such as ‘Goldmound’ provide attractive golden or lime green foliage.
Spirea needs little pruning; thin the oldest stems to maintain vigor and reduce crowding. Cultivars such as ‘Magic Carpet’ and ‘Double Play’ are short and compact.
Growth: 2 to 6 feet tall
Conditions: full sun or partial shade and well-drained soil
Hardy: Zones 3 to 9
SUMMERSWEET, AKA SWEET PEPPERBUSH (Clethra alnifolia)
Nothing is sweeter than this native blooming in a shady spot. Its fragrant pink or white flowers in slender racemes 4 to 6 inches long have a wonderful, haunting fragrance and stand up like birthday candles against lustrous green foliage. In fall, the leaves turn to a lovely, showy gold.
Summersweet spreads slowly by suckers; shape it and control sprawl by cutting weak wood to the ground in late winter or early spring. Look for ‘Sixteen Candles’, dwarf ‘Hummingbird’, or pink ‘Rosea’.
Growth: 3 to 8 feet tall
Conditions: partial to full shade and moist, acid soil
Hardy: Zones 3 to 9
To Prune or Not?
“Americans overrun,” John Brookes, a famous British gardener, once said. So, restrain yourself, prune cautiously, and step back to evaluate your work after every few cuts. Get rid of any dead wood. This is satisfying and makes it easier to spot other dull, dead branches and eliminate twiggy tangles.
Unless you are reshaping a hedge, just thin the shrubs to give them breathing room and exposure to light. Your goal is to allow the shrub to take its natural shape and show to its best advantage.
Normal maintenance pruning on a flowering shrub must be timed to its bloom cycle. The general rules: Shrubs that bloom on old wood should be pruned immediately after they flower. Shrubs that bear flowers on new growth should be pruned when they’re dormant in late winter or in early spring.
Placing and Planting
From a design point of view, shrubs should be planted where they can be enjoyed. For summer shrubs, this might mean near the porch, patio, or pool or amidst a perennial border. Choose shrubs matched to your hardiness zone and give them the sun, for birds and tolerates soil, and moisture they prefer, so that they won’t need coddling.
Whether your shrubs arrive with bare roots, come balled and bur lapped, or were container-grown, be sure to loosen and untangle their roots. Prepare a hole two to three times larger than the root mass, amend the soil, add fertilizer, set the plant at the height that it was in the container or at the nursery, and water immediately. Be protective: Shield the shrub from full sun and wind and keep watering every few days. Then mulch.