Greenspace: Why We Should Praise Petunias

Lawn and roses provided the stage for a spectacle of petunias in mid-summer – a geometric picture distinct from the gallery of relaxed suburban arts and crafts gardens in our street. Petunias, and annual bedding plants generally, are hardly vogue in gardens today. Their disappearance perhaps reflecting changing values, lifestyle and taste rather than the oft-cited changing urban density or maintenance costs.

While the petunia has long been a quintessential bedding plant, in native habitats in Argentina and Uruguay the flower conceals that potential. The name derives from the Indigenous Tupi-Guarani language groups (that also gave us jacaranda, jaguar and tapioca) and refers petunia as an inferior tobacco – an allusion to both the botanical and cultural relationship between Petunia and Nicotiana that are both in the Solanaceae (or nightshade) family (along with Australia’s kangaroo apples and bush tomatoes, potatoes and true tomatoes and a host of well-known garden plants).

Petunia was scientifically named by Antoine Laurent de Jussieu at the Jardin des Plantes in Paris from a specimen collected by Philibert Commerson in Montevideo, Uruguay. Commerson had accompanied Louis-Antoine de Bougainville as the naturalist on France’s first official expedition to the Pacific although he’s more famous from the notoriety he achieved when his valet and assistant on the voyage, Jeanne Baré, was exposed as a woman while in Tahiti (en route to becoming the first woman to circ umnavigate the world). Scottish horticulturist John Tweedie is credited with introducing petunias to horticulture by sending seeds of the white-flowered species Petunia axillaris (then known as P. nyctaginaflora and the light purple-flowered species Petunia integrifolia (also known as P. violacea) to Europe from Argentina in 1825. The first horticultural hybrid petunias were bred from these two species by Quaker plantsman James Atkins at his nursery at Painshill, Gloucestershire in 1834. Correctly these should be known as P. X atkinsiana although P. X hybrida is more commonly applied.

The concealed potential of petunia’s genotype has subsequently shown itself marvellously mutable to breeding – new colours and patterns, larger and double flowers and sweet scents have continued to lure breeders and gardeners.

While the first doubles appeared around 1900 they were unstable with only 20 to 30 per cent of doubles appearing from seed. By 1934, the Japanese Sakata Seed Corporation illustrated their understanding of Mendelian inheritance and bred the first consistently fully-double petunias – All Double Victorious. Steady progress in petunia breeding saw the first true red petunia, Comanche, from Pan American Seed in 1953, and the first true yellow petunia, Summer Sun, released by Goldsmith Seeds in 1977. In 1995, the Pan American seed company introduced Purple Wave – a trailing cultivar bred by Kirin Brewery in Japan (unexpectedly perhaps but Kirin applies its fermentation capabilities in a range of areas including plant genetics and bioengineering). Gothic gardeners have had to wait over a century for the release of a black petunia by Ball Colegrave (a subsidiary of Ball Horticultural Company) in 2011 sold variously as Black Velvet and Black Cat. While the colour is technically a deep purple the flowers are convincingly black. The boldest petunia project is for Circadia – a petunia that will engage the plant’s circadian rhythms to switch different genes on and off to express different colours during the day. This vision of a floral clock led Nikolai Braun and Keira Havens to establish plant biotech company Revolution Engineering. However, Circadia remains in the lab at this stage.

Petunias deserve closer attention. Georgia O’Keeffe’s plantings of purple petunias in her garden at Lake George in 1924 allowed her to make a closer study of blue – perhaps the most important colour in her life – and resulted in Petunia No. 2 in 1925, a prelude to her substantial body of large format flower paintings. She famously observed, “I made you take time to look at what I saw and when you took time to really notice my flower you hung all your own associations with flowers on my flower and you write about my flower as if I think and see what you think and see of the flower – and I don’t.”

Petunias embrace a diverse range of growth forms and flowers making petunias ideal in courtyards, window boxes, hanging baskets and pots as well as in landscape gardens. Petunias are commonly treated as an annual, although petunias are as often perennial in Australia’s climate. While modern varieties and horticultural technologies reduce labour and make success more certain, choosing a petunia is difficult and might be compared to choosing a rose. The journey is most likely to begin by exploring local gardens and nurseries, and seed and nursery catalogues to explore what’s available as seed or plants. Closer examination of what’s been derided as a mundane bedding plant, as Georgia O’Keeffe found, will be rewarded by a new appreciation of the petunia’s diversity and beauty.

@StephenJForbes