By Norman Winter
Horticulturist
Central Mississippi Research & Extension Center

The petunia has been one of the most popular annual flowers ever to grace our gardens. Whether edging a flower bed, covering bare ground, or spilling over a container or hanging basket, petunias give us some of our best color.

Taking into consideration the new vigorous petunias like Purple Wave and Surfinias, the petunias we know today are a far cry from the ones our ancestors grew.

Two species of petunias were discovered in South America in the 1700s and early 1800s. Soon after, breeders in Germany and England began crossing them to try to come up with more colors and larger flowers. It was not until 1953 that the first red petunia came on the market. The first yellow petunia made its debut in 1977.

The floribunda series came about in 1983 with the introduction of the Madness series. That same year Pan American Seed introduced Purple Wave, which became an All American Winner for 1995 and started a new class of spreading petunias.

But when you go to your garden center for petunias and see the terms floribunda, grandiflora, multiflora, spreading and milliflora, what will it mean to you?

The gardening world became infatuated with the class called grandiflora. These petunias have the largest flowers with 3- to 4-inch blooms, and they sometime become sprawling plants. There are single- and double-flowered grandifloras. These do best in cool weather.

The multiflora class performs better than most others in adverse weather conditions, especially hot or wet spells. They may be single or doubled flowered but are smaller than the grandifloras with flower sizes of 1 to 3 inches.

The floribunda is basically an improved multiflora. Their flowers are slightly larger and produced in abundance. They flower earlier like the grandiflora but are much more tolerant of weather. These are excellent for mass plantings.

The milliflora class was coined in 1996 with the debut of the Fantasy series. These petunias are about 2/3 the size of normal petunias with flower sizes of 1 inch or less. They produce flowers so abundantly they literally cover the plant. They are excellent for hanging baskets and containers.

The spreading petunias have caught my fancy in recent years. These are the flowering ground covers like the seed-propagated Purple Wave and the vegetative-propagated Surfinias and Supertunias.

Pick a site in full sun six hours or more daily if you want to have beds that look like the "Year of the Petunia." They will grow adequately in part shade, but you get part bloom as well.

Even though petunias thrive in a variety of soils, they do best in beds with a light, well-drained landscape mix available at any garden center.

When you buy your transplants, select a flat in bloom to guide you for color, and then buy the flat of that variety not yet in bloom. These will adapt more readily to your bed.

Space the multifloras, grandifloras and floribundas about 10 inches apart. Space the spreading petunias like Purple Wave 20 inches apart and the millifloras 6 to 10 inches.

Spread a good layer of mulch around the plants to prevent mud from spattering on the flowers, to retain moisture and to discourage weeds.

Petunias have many uses in the landscape. Edge a perennial border with the compact millifloras or floribundas. Plant them on the ends of vegetable gardens and around those growing on trellises. There bright color will look great in contrast to the green leaves of the vegetables.