The petunias we know today are a far cry from those that first appeared in 19th century gardens, although they're all based mainly on two species that were discovered in South America in the mid-1700's and early 1800's: White-flowered Petunia axillaris and purple-flowered Petunia violacea. Introduced into Europe in the early 1800's, these species weren't spectacular garden flowers--they were lanky and rather small-flowered--but breeders even then, especially in Germany and England, began crossing them in search of larger flowers and more colors. The result was the garden petunia--a group of plants in exciting colors, some with large, sometimes double flowers, others with fringed single flowers. Referred to as Petunia x hybrida, the plants weren't hybrids as we know the term; they were chance crossings of species. Burpee's 1888 catalog listed a 'Black-throated Superbissima', which had deeply veined, dark crimson-purple petals and a black throat.
Double flowers, as Vaughan's Seed Catalog of 1900 noted, occurred in only 20 to 30 percent of the plants grown from seed; the rest would be large singles. It took until the 20th century for hybridizers to bring the genetics of Mendel to bear on petunia plant breeding.
At the beginning of this century, breeders in Japan began researching petunias, and in 1934, Sakata Seed Corporation bred the first consistently fully-double petunias. 'All Double Victorious' mix, considered a breeding breakthrough, was an All-America Selections Winner that year. Flowers were as large flowered as double petunias of today. It was a grandiflora type with fringed petals. Sakata Seed Corporation managed to interpret and apply Mendel's law of gene dominance in the search for a fully-double petunia, one that would come true to type from seed.
During the 1930's, German seed companies bred grandiflora petunias--all open-pollinated varieties--and greatly expanded the diversity of the plants, especially in the area of colors. The 1939 Benary Seed Growers catalog offered an open-pollinated, dark purple, white-edged petunia--only recently, in the '90's, has this unusual bicolor combination been introduced as a hybrid. The history of the hybrid petunia involved an exchange of information--individuals and companies learning from, and building on, what others had done.
In the late '30's, Charles Weddle, of W. Atlee Burpee & Company, applied the same law in his search for the fully double petunia. When he discovered the key--that the gene for doubleness was a dominant gene and crossing a true breeding double-flowered petunia with a compatible petunia would yield seeds that produced all double-flowered offspring--the production of modern-day petunias was on the way. After the interruption of World War II, work began again in earnest. Doubleness wasn't the only characteristic breeders were looking for. They also wanted larger flowers, and more of them for a longer time, more compact plants with better branching habits, better disease- and weather-resistance--many petunias, even today, look bedraggled after a rainstorm. Fred Statt, of Harris Seeds, worked on disease-resistance, while still coming up with petunias that looked beautiful. In the early '50s, Weddle and Claude Hope, founders of Pan American Seed Company, went on to hybridize double and single grandifloras and multifloras--these really revolutionized the bedding plant industry.
In 1949, Weddle won an AAS award for the first F1 single-flowered multiflora, 'Silver Medal'. Crossing a grandiflora with a multiflora produced a hybrid plant that was vigorous and desirable, and in 1952, PanAmerican's 'Ballerina', the first F1 grandiflora, won an AAS award.
The breeding work involved with F1 hybrids and the seed production made the seed very expensive, but it also allowed hybridizers to greatly improve the plants over their species or open-pollinated relatives. The cost and size of the seed increased the chances for failure on the part of the home gardener and made the purchase of bedding plants more desirable. Coincidence or not, garden centers began to spring up around the country in the 50's, and petunias quickly became gardeners number one choice for annual color.
Changes and improvements have continued for decades. The first truly red petunia, a multiflora called 'Comanche'--bred by PanAmerican Seed--was brought out in 1953. The first yellow petunia, called 'Summer Sun', was bred by Claude Hope and introduced in 1977 by a relatively new company, Goldsmith Seeds. A new class of petunias, called floribunda, was created by Ball Seed Company in 1983, and introduced the 'Madness' series. In 1995 'Purple Wave' was introduced as an AAS Winner and began a new class of spreading petunias. The new variety was bred by Kirin Brewery in Japan and introduced by PanAmerican Seed Company. An additional new class, milliflora, was bred by Goldsmith in 1996. These different classes may bring about a revolution in petunias, leading to changes that completely transform the garden petunia we now know.