Plant Story--Colorful Petunias for Summer Gardens

Petunias are everywhere: in summer street plantings, in decorative pots, in hanging baskets. And yet, petunias are anonymous. Poor petunia, we barely notice you.

red petunias

potted petunias

The genus Petunia (tomato family Solanaceae) is a group of about 35 species native to the Americas. The cultivated petunias are a hybrid, called Petunia xatkinsiana (also called Petunia hybrida) that formed in Europe from Petunia axillaris (white flowers) and Petunia integrifolia (previously P. violacea, purple flowers). These are Argentine species which do not hybridize in nature.  

Apparently petunias were first noticed by Spanish explorers in the 17th century, who made a note but did not think them interesting enough to send seeds or live plants back to Europe. They did record Native name for the plants, petun, which means tobacco in the Tupi-Guarani language of northern Argentina. Petunias are not a tobacco, but tobacco is also in the plant family Solanaceae and they share many characteristics, so the name was a form of saying, "oh, that, that is a tobacco" like I would say, "oh, yes, that's an aster." Petun was Latinized as Petunia in the scientific name, which became its English common name. 

A hundred years later, French explorers noticed petunias and brought a few back to Europe. Generally they languished in botanical collections. But in the early 1800s European gardeners tried breeding them for bigger flowers, and they were the ones that created Petunia xatkinsiana. They produced doubles and colors beyond the original white and lavender--red, yellow, blue, deep purple, and bicolored. They were very successful. Petunias took off as desirable garden plants. Further breeding in the 20th century produced more shades and patterns. While Petunia xatkinsiana dominates the garden trade, today you can find other species of Petunia for sale, usually with smaller somewhat different flowers. The prairie petunia is the closely-related genus Ruellia; no species of the genus Petunia are native to North America. 

Petunias are quite drought-resistant and grow well in under many conditions. They will tolerate a little frost but are grown as annuals in most temperate regions.

The leaves are slightly sticky, which is believed to protect them from insects. I dislike handling them. However, both deer and rabbits are not repelled by the stickiness and will eat petunias. Petunias are recommended as a companion plant for squash and beans because they distract squash beetles, bean beetles, and potato beetles from the vegetables. 

Online you can read that the Maya and the Inca believed the scent of petunias had the power to ward off underworld monsters and spirits. I can't confirm that, and in fact, the genus Petunia is found only in central South America: northern Argentina, Uruguay, and southern Brazil, no higher than the foothills of the Andes. So the high-elevation Inca probably did not know of them, and the Maya were too far north, across the the vast Amazon lowlands. The folklore may be simply attributed to the wrong Native American groups, since the name we have for them comes from Tupi-Guarani, who live where petunias are native. 

In their native Argentine grasslands, different species of Petunia were pollinated by bees, hawkmoths,  butterflies, and hummingbirds. The cultivated varieties include plants which attract those same groups of pollinators, but also some with flowers so modified that they are not particularly attractive to any pollinator or which have doubled petals that make it difficult for insects to reach the nectar. Watch to see what is visiting the flowers of petunias growing near you.

They reached England in time to be included in some versions of the language of flowers, a Victorian conceit in which flowers had specific meanings so that if you sent or gave flowers to someone, the choice of flowers added a message. If you receive petunias, you should interpret it as "Your presences soothes me."

 Since they are tough and colorful, you find them everywhere. 

Petunias grow quickly and produce many seeds, so they have participated in decades of botanical research, both working out basic biology and for better garden flowers. Which is why petunia was the plant used to demonstrate inserting a gene (from corn, Zea mays) and turning on reaction that created orange flowers. Which showed up in gardens, creating a quite scandal. And today, you can buy petunias that glow in the dark with a gene from mushrooms. I will write about petunia as a "laboratory rat" next week.

Notice how many different colors and patterns of petunias you see in an ordinary day. It is quite amazing.

Comments and corrections welcome. 

References

Allardice, P. 1993. A-Z of Companion Planting. Angus&Robinson, Publishers. Pymble, NSW, Australia.

Fox, K. L. and J. R. Sullivan. 2024. Petunia. Flora of North America. online: link  accessed 6/21/25

Monroe-Fischer, M. (2025) email: quoting M. Kirby A Victorian Flower Dictionary.

Rodrigues, D. M., L. Caballero-Villalobos, C. Turchetto, R. Asisis Jacques, C. Kuhlemeier and L. B. Freitas. 2018. Do we truly understand pollination syndromes in Petunia as much as we suppose? AoB Plants. online link accessed 6/22/25

Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 14, July 2017 [and more or less continuously updated since]. link   accesssed 6/21/25

Kathy Keeler

A Wandering Botanist

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