http://gardening.about.com/od/plantprofiles/tp/Petunia_Choices.htm They have more information if you are interested.
Today's petunias offer enormous variety: single and double blooms, ruffled or smooth petals, striped, veined or solid colors, mounding and cascading habits and even some with fragrance. Most of the petunias sold today are hybrids, developed for specific design purposes. It's hard to go wrong choosing a petunia these days, but here's some advice for pairing your petunia with your need.
1. Grandiflora Petunia
Grandifloras are one of the oldest varieties. These petunias grow eight to twelve inches high and have the large (4-5"), wavy-edged blossoms that petunias first became known for. They can be single or double. Grandiflora petunias have the largest flowers, but the flowers get pummeled by rain and are unpleasant to deadhead. Grandifloras work well in both beds and containers.
2. Multiflora Petunia
Multiflora petunias have a more compact growth habit than grandifloras. The flowers are smaller (2"), but more prolific and they hold up better against rain. There is also a wide range of colors. Multiflora petunias are a better choice for garden beds and also work well in containers.
Hybrids of grandiflora and multiflora petunias often share qualities. The "Madness" series that was introduced in the 1970s had grandiflora sized flowers and multiflora weather tolerance. A whole new category was created to describe them, the 'Floribundas'. Today you will find floridbunda petunias with either small or large flowers.
3. The 'Wave' Petunia Series
The 'Wave' series created quite a stir when first introduced and keeps improving. 'Wave' petunias grow only 6" tall but can spread to 4'. They make wonderful groundcovers and trailers for containers. Although Wave petunias don't need deadheading, they do wear out in the hottest part of the summer and some pruning will revive them. There is also a 'Tidal Wave' series, which tends to stay a bit more upright.
4. Supertunia Petunias
The 'Supertunia' series is vegetatively propagated, meaning it is grown from cuttings, not seed. Supertunias are part of the Proven Winner series. Vigorous growers and bloomers, they require frequent feeding to stay at their peak. But if you feed them, they will bloom and bloom. Supertunias are also weather tolerant.
5. Cascadia and Surfinia Petunias
'Cascadia' and 'Surfinia' are 2 more popular types bred for their trailing habit, vivid colors and prolific flowering. You'll find lots of interesting shading and veining with these petunias. They are also easy care, spreading to about eighteen inches. These petunias are best suited for hanging baskets and window boxes.
6. Calibrachoa (Million Bells, Superbells)
'Calibrachoa' (Million Bells or Superbells) look like tiny petunias, but they are actually an entirely different species. However they may just suit your purpose in a hanging basket. The tiny flowers cover the foliage and Calibrachoa hybrids share the best traits of hybrid petunias: long blooming, no deadheading and weather tolerance. Till next time, this is Becky Litterer from Becky's Greenhouse, Dougherty, Iowa