Top 5 Annuals for the South

­Although they are known for being one of the more popular American houseplants, begonias are also frequently used in flowerbeds or hanging pots. The popularity of begonias is due to their general pleasantness. They are easy to grow in fertile, adequately drained soil, and their flowers and foliage are very attractive, especially when planted in large groups.

Depending on the species, begonias tend to grow ­anywhere between 8 inches (20 centimeters) and 2 feet (61 centimeters) tall, with flowers white, yellow, orange, red or pink in color. The most widely grown species of begonia is the wax begonia, which is known for its hardiness and durability. The wax begonia can survive the cooler temperatures of the early spring and continue to bloom through the pulsing heat of a southern summer. Similarly, although wax begonias may fare better with a little bit of shade, they can still grow well out in the open sun. Wax begonias have heart-shaped leaves -- often with a red or mahogany tint -- and flowers of white, pink or red. For ideal results, wait until after the last frost of the winter to transplant any begonias that may have been inside for the winter, and be sure to arrange the plants 6 to 8 inches (15 to 20 centimeters) apart [source: Clemson Extension Home & Garden Information Center].

While wax begonias may thrive in the summer heat, tuberous begonias do not. They will wilt in the peak of summer. Many gardeners plant tuberous begonias in early March and then again in September to add color to the building and waning weeks of summer. Tuberous begonias also need much more shade than wax begonias, especially when germinating, and require more watering and fertilization. Tuberous begonias grow to be between 12 to 18 inches (30 to 45 centimeters) tall, with flowers 2 to 4 inches (5 to 10 centimeters) wide. They're white, yellow, orange, red and pink in color [source: Kessler].

In addition to wax begonias and tuberous begonias, there are several other species of begonias, including many low-maintenance hybrids and hardy begonia, a leafy perennial.

­For the beginning gardener, cosmos are an ideal plant. There are many different species of cosmos, but just about all of them germinate very quickly, grow very rapidly, and are hardy enough to tolerate an early spring frost and the summer's blazing sun. Most cosmos grow to be anywhere from 2 to 7 feet (60 to 215 centimeters) tall -- depending on the species -- and tend to be placed in the rear of garden arrangements.

There are two predominant species of cosmos in the U.S. South -- cosmos sulphureus (yellow cosmos) and cosmos bipinnatus (pink cosmos). Although cosmos may perform better in drier, hotter environments, they will grow just about anywhere they can consistently receive a day full of sunshine. In fact, cosmos lavished with too much water and shade become frail and bloom inconsistently [source: The Gardener's Network].

Yellow cosmos grow to be between 2 to 4 feet (60 to 120 centimeters) tall with flowers of red, orange or yellow, and long, narrow green leaves. Yellow cosmos are traditionally planted in spring, usually raked into the soil, and will germinate once the soil reaches a temperature of 70 degrees Fahrenheit (21 degrees C). Yellow cosmos only take a few weeks to germinate, and will bloom very quickly after. Once the flower has bloomed, yellow cosmos require little watering or maintenance. If planted in fertile soil outside of its native climate, yellow cosmos will grow very lanky and tall. Likewise, using fertilizer on yellow cosmos will produce a much leafier, taller plant.

Pink cosmos share many of the same growing tendencies as yellow cosmos, but are especially popular in the sandier soils near the Gulf of Mexico and the Atlantic Coast. Pink cosmos range in height from 1 to 7 feet (30 to 215 centimeters) tall depending on the species and growing conditions, with flowers white, pink, rose or red in color. Though they both thrive in similar climates and soils, pink cosmos are generally not as hardy as yellow cosmos, and often require stakes to hold their stems upright. Pink cosmos are often used in grassy, meadow-like gardens, quite often because their nectar is known to be one of the best for attracting butterflies [source: Scheper].

­Like begonias, marigolds are a classic annual in American gardening. Marigolds are easy to grow, hardy enough to bloom all summer long and are able to grow in most North American climates. Marigolds grow to be between 8 to 40 inches (20 to 100 centimeters) tall depending on species and growing conditions, with flowers of yellow, gold, orange and red.

Most marigolds used in American gardening today are cultivated hybrids -- many with multiple colored flowers and scented leaves or flowers. The two predominant natural species are African marigolds (also known as American marigolds) and French marigolds.

American marigolds have large, dense, ruffled flowers that can measure up to 5 inches (13 centimeters) across and range in color from yellow and gold to orange. American marigolds can grow to be 3 feet (90 centimeters) tall and, like many other large gardening flowers, are ofte­n arranged in the back of the gardening bed. Native to South American and Mexico, American marigolds have fine leaves, dark green foliage and an unpleasant scent [source: Clemson Extension Home & Garden Information Center].

French marigolds are smaller and bushier than American marigolds. They grow between 8 to 16 inches (20 to 50 centimeters) tall with smaller, less dense flowers of orange, red and crimson.

No matter the species or hybrid, marigolds are ­fairly easy to grow just about anywhere in the U.S. Southeast. Marigolds need a lot of sun and well-drained, fertile soil to grow to their full potential. Although marigolds are hardy enough to bloom through the summer, you should still wait until after the final frost of winter to plant them in your garden. Once you've planted your marigolds, be sure to water them thoroughly and water at least once a week once they've bloomed.

French marigolds are often used as garden borders, in container plantings, and as decorative cut flowers. Some gardeners plant marigolds to help prevent harmful insects from inhabiting their gardens -- despite multiple studies that claim marigolds have no impact on insect damage [source: Clemson Extension Home & Garden Information Center].

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­Pansies are small half-hardy garden flowers that have been traditionally regarded as too weak to prosper through the summer sun and heat. More recently however, many gardeners have begun to use pansies as a flower to bring added color to the cooler spring and fall, and have discovered that in warmer climates, pansies can grow through the winter [source: PLANTanswers].

Pansies have colorful flowers and rich green foliage. There are a multitude of species and ­hybrids, many cultivated to add to the assortment of colors available. Native species of pansies are red, ­yellow, blue and purple in color, but hybrids have expanded the palette to pink, orange, white and black.

Pansies are planted in the waning months of fall to touch out the winter and bloom first thing t­he following spring. If you are planting pansies in the spring or end of summer, be sure to plant them in the shade where they won't be damaged by the sun.­

As a top-selling gardening flower in the U.S., pansies can be found at just about any gardening center or greenhouse -- and they should have countless species available in packs or bedding. When planting your pansies, be sure that they are in a location that receives a lot of morning sun and has well-drained, acidic soil.

­Petunias are yet another standard in American gardening. Native to South America, petunias have been a staple in American gardens long enough for certain strains to naturalize in much of the U.S. South, and for hundreds and hundreds of hybrids to be developed.

Petunias range in height from 6 to 18 inches (15 to 45 centimeters) with flowers from 1 to 5 inches (2 t­o 12 centimeters) in diameter. Due to extensive hybridizing, petunias are available in just about any color, with many variations featuring contrasts and patterns in the flowering, as well as scented foliage. Petunias are durable flowers that will bloom from early spring to late fall in full sunlight. They grow best in well-drained, light soil, though ­they can be successful in most other soils as well.

Petunias and often distinguished as being either grandifloras or multifloras. Grandifloras are often planted early in the spring and near the end of summer, as they cannot survive the heat of the average southern summer. They have large, ruffled double-flowered blossoms that are vulnerable to damage during periods of extreme heat and heavy humidity. Furthermore, grandiflora petunias often require additional attention to maintain the appearance of their large flowers. Multiflora petunias are much more resilient than grandiflora petunias, and will retain their vibrant colors through the peak of summer. Multiflora petunias have smaller flowers than grandiflora petunias. They are resistant to petal blight and generally easier to maintain [Source: Scheper].