In the Garden:
Upper South
July, 2008
Regional Report

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Crape myrtles and hydrangeas are just some of the wonderful summer-blooming trees and shrubs.

Bloomin' Summer Favorites

Every season has its joys and pleasures, albeit in different ways. In spring, trees and shrubs knock your socks off with their spectacular beauty. In summer, the effect is generally more subtle, but I find that I look forward to it just as much. Certainly, there are lots of annuals and perennials providing plenty of flowers, but there is something about the extra dimension that summer-blooming trees and shrubs add to the garden. Some of these are well known and widely used, while others are more obscure. The following descriptions are by no means a complete list, but they might inspire you to add some summer bloomers to your garden.

Hydrangeas
Abundantly producing white, pink, or blue flowers, hydrangeas have become one of the most popular of all shrubs in the last few years due to the introduction of Hydrangea macrophylla varieties that bloom on new wood, making them adaptable to colder climates. 'Endless Summer' started the trend, but companies are continually introducing new varieties each year. The 'Forever & Ever' series is also excellent, with red, double, pink and white bicolor, and white forms.

Other hydrangeas are stunning in the summer garden, too. Grown on a standard trunk, the Peegee hydrangea (H. paniculata) is an old-fashioned favorite. 'Tardiva' and 'Pink Diamond' are two newer varieties, but it is the recently introduced 'Pinky Winky' that is garnering all the press. It bears 12- to 16-inch, two-toned, pink and white flowers on strong, upright red stems from midsummer on.

Oakleaf hydrangea (H. quercifolia) is native to eastern North America and is one of the most handsome of landscape plants with its 6-foot-plus rounded shape and lobed leaves that turn rich burgundy in the fall. The spiked flower clusters are white aging to purplish pink. 'Alice', 'Snowflake', and 'Snow Queen' are popular varieties. 'PeeWee' and 'Sike's Dwarf' are smaller forms, reaching 3 feet or so. 'Little Honey' has gold leaves.

Smooth hydrangea (H. arborescens) is another eastern North American native. The form most often found in garden is 'Annabelle', with large, rounded heads of white flowers that start blooming in June. The plants grow 3 to 4 feet tall. Other forms include 'Hayes Starburst' with double florets and a long bloom period, 'Radiata' and 'White Dome' with lacecap flowers, and 'Samantha' with extra-large flowers.

Rose-of-Sharon
Rose-of-Sharon (Hibiscus syriacus) is a seemingly indestructible, old-fashioned shrub that has seen any number of varieties come and go over the decades. The stiffly upright, multi-stemmed shrubs grow to 12 feet tall and bear flowers in single or multiple shades of white, pink, red, and purple. The biggest downside to the older forms is that they relentlessly reseed all over the garden. The USDA and the National Arboretum have introduced cultivars over the years, two of which are outstanding garden plants. Plus they're sterile so they don't produce seeds. 'Helene' has white flowers blushed with pink and red throats, while 'Diana' has pure white flowers. Because they produce no seeds, these varieties bloom until frost. An added bonus is the deep green, glossy foliage. Another possibility is 'Li'l Kim', a dwarf form growing to 4 feet tall with red-centered white flowers that last three days rather than the typical one day.

Butterfly Bush
Like the rose-of-Sharon, butterfly bush (Buddleia davidii) has the annoying habit of reseeding, some cultivars worse than others. A study done several years back by Longwood Gardens in Pennsylvania found that 'Orchid Beauty' and 'Summer Rose' were the only two varieties that produced very few seeds. The new dwarf forms from the English Butterfly Series, which grow to 4 feet tall, have not produced any seedlings so far in my garden after several years growth. 'Peacock', 'Purple Emperor', and 'Adonis Blue' are the choices in this series. 'White Ball' also has been reported to produce few seeds.

Summersweet
How could you not fall in love with a plant called summersweet, especially when its lovely floral fragrance permeates an entire garden? Clethra alnifolia, native from Maine to Florida, bears its spikes of tiny white or pink flowers during July and August on rounded shrubs growing to 8 feet tall, depending on the variety. The lustrous, dark green leaves turn golden yellow in the fall. A number of cultivars have been selected. Of these, look for the 3-foot form called 'Sixteen Candles', rose-pink 'Ruby Spice', late-flowering 'September Beauty', and the profusely blooming 'Chattanooga'.

Bush Honeysuckle
Okay, this one won't stop traffic, but bush honeysuckles (Diervilla sessilifolia and D. lonicera) are adaptable and versatile plants that can grow in some pretty tough situations. They aren't really honeysuckles, but they do have small yellow flowers from June to August that are highly attractive to butterflies. They form rounded shrubs 3 feet or so tall. In fertile soil they will quickly spread by runners, but they are more polite in poor soil.

Seven-Son Tree
Widely acclaimed in the garden press, Heptacodium micomioides was introduced from China into the U.S. in 1980. It forms a multi-trunk tree growing to 20 feet or so tall with exfoliating bark. Airy clusters of white flowers are borne in August, followed by red calyces (the leafy parts behind the flowers). My mother acquired a plant some 20 years ago, and I have mixed feelings about it. It sends out growth at awkward angles and always has some dead limbs. It has remained in the garden, not only for sentimental reasons, but because it also makes a viable contribution to the garden, faults notwithstanding.

Sourwood
For those who prefer to go native, few trees can compare with the sourwood from the southeastern United States. Growing somewhat pyramidal to 30 feet tall with gently drooping branches of lustrous, dark green leaves, the sourwood puts on a show in summer with clusters of flowers resembling lily-of-the-valley. Difficult to produce in the nursery and temperamental when planting, it is not a plant for the faint-hearted, but well worth the effort.

Crape Myrtle
No shrinking violet here, since crape myrtles (Lagerstroemia x indica, are some of the most spectacular of garden plants when in flower. In the south, they are widely used as small flowering trees. Moving north, they become more shrubby, often dying back to the ground in winter, but bravely sending up new growth that flowers in summer. There are hundreds of cultivars, so, in general, it's best to go with what a reliable local nursery offers. If you want a small form, look to the Razzle Dazzle Series of dwarf crape myrtles, which are hardy to Zone 6.

Chastetree
Another plant that varies from shrub-like to a small tree, depending on the climate, is the chastetree (Vitex agnus-castus). Fortunately, it blooms on new growth, producing long, spiky plumes of tiny lavender flowers in summer. Plants grow to 10 feet tall and as wide, with gray-green, aromatic leaves.

Bluebeard
There's something about blue flowers in the garden, and from summer's height until it wanes, bluebeard (Caryopteris x clandonensis) puts on a serious show. Although growing only about 2 to 3 feet tall and wide, the rounded mounds will be covered in blooms, especially if plants are cut back in late winter to promote new growth. There are a dozen or so widely available varieties, mainly varying in flower and leaf color. 'Longwood Blue' is noted for silvery foliage and sky-blue flowers. 'Grand Bleu' and 'Petit Bleu' have dark blue flowers and dark green leaves; 'Sunshine Blue' has yellow foliage with amethyst-blue flowers.

Tamarix
Tamarix ramosissima was in our garden when I was a child, and I always enjoyed its gray-green, scale-like leaves and feathery rose-pink flowers. That plant is long gone, but it's on my list to find and grow again. Tamarix is a widely adaptable plant that grows as an irregularly shaped shrub or small tree growing 10 to 15 feet tall.

Last, But Not Least
Of course, the ultimate summer-blooming shrub is the rose, most notably the shrubby types that bloom almost continuously. Knock-Out and its kin such as 'Home Run' have made this a no-brainer, but don't overlook other varieties that are just as good, such as the Flower Carpet Series, and 'Carefree Beauty', as well as older roses like 'The Fairy'.


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