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].