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Top 10 Summer Plants

The sunflower is one of the obvious choices for summer, but what are some other popular plants that thrive in warm weather? See more pictures of annual flowers.
Cornelia Doerr/Getty Images

What makes a plant great is, of course, subjective. Everyone has his or her own favorites. When looking for flowers for your summer garden, what matters to you? Do you want something that keeps blooming all summer? Do you like "set and forget" types of flowers that return every summer? Do you value the fragrance that summer heat releases from some blooms?

In this article, we'll look at easy care ornamentals with luscious flowers that bloom all summer. From extravagant and romantic to petite and perky, from flowering evergreens to old-fashioned favorites, there's something here to enhance your summer outdoor atmosphere.

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Remember, all plants have a climate zone, also known as a hardiness or growing zone, which helps you get an idea of the temperature extremes a plant can endure. The United States Department of Agriculture (USDA) issues a map that divides the United States into 11 climate zones, where zone 1 is the coldest and zone 11 is the warmest, so you can see if a certain plant can survive in your area [source: United States National Arboretum].

Gardenias are a classic summer plant.
Gardenias are a classic summer plant.
©iStockphoto.com/Dewitt

Gardenias (Gardenia jasminoides) are like basic black -- one color, timeless style. Introduced into the U.S. from China in 1854, this tidy shrub exhibits shiny evergreen leaves with white, fragrant, rose-like blooms [source: Church]. Hardy to zone 7, gardenias like rich, acidic soil and atmospheric moisture, such as you'd get around the coast or the humid South. The blooms are short-lived, but they're also ever-renewing. Where one flowers fades, another waits, wrapped in a spiral of sepals, to take its place. Plant gardenias where you can enjoy their fragrance, which is reminiscent of jasmine (hence the "jasminoides" in its scientific name).

Some gardenia varieties reach 10 feet (3 meters) high and 6 feet (1.8 meters) wide. In climates colder than zone 7, you can grow dwarf varieties, such as G. jasminoides "Radicans," in containers and bring them inside for the winter [source: Church, O'Sullivan].

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Gardenias provide an added bonus. Unlike plants that go dormant in winter, gardenias stay green and active during colder months. That means they're photosynthesizing -- and cleaning carbon dioxide from the atmosphere -- every day of the year.

Do you admire the classic elegance of roses but think they're too much trouble? Read about a fuss-free rose on the next page.

Forget the fussy cultivars, or varieties of plants selected for specific traits, that need to be sprayed with chemicals every week. Rose enthusiast William J. Radler worked for decades to hybridize a rose that doesn't need continuous care. The rose he patented as Rosa hybrida "Radrazz" was offered commercially as the "Knock Out Rose" in 2000. A cherry-red, ever-blooming shrub rose with 5-11 petals, it was named the All-American Rose Selection for that year and has remained popular ever since [source: All-America Rose Selections]. In addition to disease resistance, Knock Out roses show tolerance for an array of adverse conditions, including heat and cold, drought and humidity, and hours of daily shade.

A group of Texas A&M University horticulturists put 116 rose varieties to the test under minimal-care conditions -- no pesticides, no fertilizers and no supplemental irrigation after establishment. At the end of the three-year study, Knock Out came out on top, earning high ratings for appearance, vigor and black spot resistance [source: Mackay].

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What's short on stature and long on bloom? Find out on the next page.

Whether they're in beds, borders or hanging baskets, impatiens (Impatiens) bring delight no matter where they show up. The small, 5-petaled annuals bloom abundantly in white, pink, lavender, red and bi-colored varieties. Gorgeous double-petal forms come in similar colors. Impatiens are the top-selling bedding plant, but some varieties reach 5 feet (1.5 meters) tall. They thrive from the Deep South to the Great Lakes [source: Armitage].

These happy little flowers need morning sun and afternoon shade. In warmer regions, they'll keep blooming well into the fall. They're annuals, but they can reseed themselves and pop up again -- somewhere in your landscape -- next year.

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Curious about what kind of soil you have? The plant on the next page can tell you.

The color of your hydrangea garden can actually tell you what type of soil you have.
The color of your hydrangea garden can actually tell you what type of soil you have.
Heather N. Kolich

Natives of North America and East Asia, hydrangeas (Hydrangea arborescens, H. macrophylla, H. paniculata, H. quercifolia) offer extravagant blooms for a variety of environments from zone 4 to 9. Their forms include climbing, shrub and wild forest giant. They produce multi-flower blooms in flat, "mophead" and cone shapes. They need full sun in northern climates and dappled shade in the South.

The color of flowers on big-leaf hydrangeas, H. macrophylla, depends on the aluminum content of the soil. Acidic soils make aluminum available, and hydrangeas in acidic environments bloom blue; those in alkaline soils bloom pink. Cultivars take the colors to extremes of red and violet. The cone-shaped blooms of H. paniculata start out white and mature to rosy-pink in the fall. H. arborescens, wild hydrangeas, have white flowers. Light up your shade garden with the giant popcorn-ball blooms of H. arborescens, nicknamed "Annabelle."

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For year-round interest, opt for the North American native oak-leaf hydrangea (H. quercifolia), named because their leaves are shaped like oak leaves. They'll give you deep green spring leaves, summer clusters of white to pink flowers, blazing burgundy fall foliage, and peeling, cinnamon-colored bark in the winter.

See the next page for another lavish bloomer.

Peonies grow best in a temperate environment.
Peonies grow best in a temperate environment.
Heather N. Kolich

Extravagant, double-bloomed peonies (Paeonia lactiflora) are staples in Chinese art. Originally cultivated for medicinal purposes, the ornamental and fragrance values eventually took precedence. During the T'ang dynasty (618-906 AD), the flowers enjoyed imperial protection. A woman's dowry frequently included peonies [source: D'Aoust, Goodrich].

The Chinese peony (P. lactiflora) came to North America in the 1830s [source: D'Aoust]. In 1907, Cornell University endeavored to untangle the names and standardize the spelling of peony varieties. Since the popular flower had been cultivated in China, Japan and Europe for centuries, varieties and confusion were abundant. The university collected and identified over 2,700 species of named peonies that had appeared in botanical literature [source: Coit].

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These heirloom flowers still grace temperate gardens worldwide. They need full sun and cold winters to stimulate their lush blooms, and they'll probably need staking. You can also cut them, however, and enjoy the flowers inside. Once established, they'll return each summer for decades.

Read about another long-storied flower on the next page.

The scent of lavender is a popular favorite.
The scent of lavender is a popular favorite.
Ross Anania/Getty Images

We associate "lavender" with a color, but the word originates from the Latin "lavare," meaning "to wash" [source: Harper]. Greek botanist Dioscorides documented use of this fragrant Mediterranean herb for bathing and medicinal purposes in the 1st century A.D. [source: Castle]. Lavender oil remained popular for bathing, perfumes and deterring lice from people and animals well into the 19th century. It's still an important crop in France, both for cash and tourism.

Lavender (Lavandula), which does bear lavender blooms, likes full sun and dry conditions. This evergreen, hardy perennial isn't plagued by many pests and doesn't mind windy conditions, but soggy soil kills it. To survive in arid environments, lavender grows deep roots. It doesn't like to be moved around.

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Lavender grows spherically, achieving almost equal height and width, which ranges from 2 feet (0.6 meters) to 6 feet (1.8 meters), depending on the variety. It's an excellent plant for borders and to anchor fences and foundations in your landscape.

Could your landscape use some vertical interest? The flowering vine on the next page may help.

Clematis bloom in the early summer.
Clematis bloom in the early summer.
Heather N. Kolich

The early summer blooming group (group 2) of the clematis family (Clematis) dishes up plate-sized flowers in a range of colors and a variety of forms -- single, semi-double and fully double. These climbing vines rewarded growers with a double-dose of flowers. The first buds form in spring on old growth. In the summer, a second crop blooms on spring and summer stems. The flowers last for days, and new flowers form throughout the summer.

Clematis in group 3 are late bloomers. They form flowers on new growth in summer and keep blooming throughout the fall. Some late-blooming varieties have flat, star shapes like the earlier bloomers, but others produce flowers that look very different. Rather than facing up to the sun, group 3 clematis may form tubular flowers, columns of bells or down-turned, nodding flowers with hood-like petals.

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Clematis is a hardy perennial that thrives in zones 3-9. It likes plenty of sun but prefers to have its roots in a shady spot. Some varieties reach 10-15 feet (3-4.5 meters) in length. They need pruning in early spring, before new growth starts.

On the next page, read about a stunning artistic inspiration.

Does any flower say "summer" better than sunflowers (Helianthus annuus)? These giants, with names like "Skyscraper" and "Mammoth," are awe-inspiring. From heights far above eye level, bright yellow, pizza-sized flowers turn their dark, seed-filled centers to follow the sun as it rides across the sky. Sunflowers need plenty of space and, of course, tons of sun. They also need staking and protection from wind, so plant them near a sheltering fence or wall.

Now, clear your mind for a moment and imagine red sunflowers. Or dwarfs with white, daisy-like petals. Or double forms with hundreds of petals crowding toward the center. These are sunflowers, too, with edible seeds and heliotropic habits (which means they turn toward the sun). The smaller varieties perform well in borders and don't require a ladder to harvest. The double and red sunflowers are fun for their diversity.

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Speaking of diversity, if you've ever entertained the idea of creating your own, unique flower, see the next page.

Name a color. There's probably a daylily (Hemerocallis) to match. Need a low-growing flower? There's a daylily for that. A tall one? There's a daylily for that. Want a star-shaped bloom, a double bloom or ruffled petals? There's a daylily for that, too.

Hemerocallis means beautiful for one day in Greek. And, in a way, it's true. Each daylily bloom shines for a day, and then it folds in the night. But with sun and daily deadheading (removal of old blooms), the plant produces flower after flower for weeks on end. Many new cultivars rebloom, offering a second show later in the season. The flowers grow on stalks from the center of long-leaved clumps, which come in evergreen and deciduous options. Large flowers and flower parts make hybridizing easy if you want to create your own daylily variety.

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You can plant daylilies spring, summer and fall, and even in winter in warmer zones. They're tough and beautiful, and there are nearly 60,000 unique varieties to choose from [source: Petit]. Stagger your beds with early, midseason and late blooming varieties, and you'll enjoy three seasons of flowers.

Finally, the next page features a stunner for your shade garden.

In shades of white, pink, lavender and red, astibles (Astilbe) infuse shade gardens with breezy drifts of color. The flowers themselves are tiny, but clusters of them rise above attractive foliage on sturdy, upright plumes. They range in size from the diminutive, 8-inch (20-centimeter) high "Liliput" to the 5-foot (1.5-meter) tall Himalayan Astilbe (Astilbe rivularis) [source: Schmid]. Most astilbes have rich green, compound leaves reminiscent of ferns, but Astilbe simplicifolia has large, simple leaves that look more like ivy. The perennial plant dies back at the end of fall, but the panicles, or pyramid-shaped clusters of flowers that grow off branches, dry to brown and remain standing, adding textural, vertical interest to your winter garden. They also complement dried flower arrangements.

Astilbes like rich soil and ample mulch. They're sensitive to dry spells; watch for droopy plumes to know when they need supplemental water. Astilbes grow and slowly spread from underground rhizomes. Different varieties are hardy from zones 3-8, and they'll return to embellish your shady spots for many years.

See links to related articles on the next page.

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