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].