Petunia

Plant Characteristics

Lifespan:	⌛	Tender Perennial"Tender Perennial" is not in the list (perennial, annual, biennial, unknown) of allowed values for the "Lifespan" property.

Cultivation

Exposure:	☼	Full sun"Full sun" is not in the list (sun, part-sun, shade, unknown) of allowed values for the "Exposure" property.
Features:	✓	Flowers
Sunset Zones:		All zones

Scientific Names

Solanaceae >

Petunia >

Petunia is a, trumpet shaped, widely-cultivated genus of flowering plants of South American origin, in the family Solanaceae. Most of the varieties seen in gardens are hybrids (Petunia x hybrida). A wide range of flower colors, sizes, and plant architectures are available in both the hybrid and open-pollinated species.

Purple Petunias

The popular flower got its name from French, which took the word petun 'tobacco' from a Tupi-Guarani language.

The origin of P. x hybrida is thought the be a hybridaization between P. axillaris and P. integrifolia. Many open-pollinated species are also gaining popularity in the home garden.

Some botanists place the plants of the genus Calibrachoa in the genus Petunia. Botanically speaking, tobacco, tomato, potato, and petunia are all in the family Solanaceae.

Read about Petunia in the Standard Cyclopedia of Horticulture

Petunia (Petun, South American aboriginal name, said to have been applied to tobacco). Solanaceae. Petunia. Small herbs, grown for their showy bloom as garden annuals. Annual or perennial, branching, viscid-pubescent, of weak or straggling growth: lvs. alternate, or opposite above, soft, entire: fls. white or purple, or in shades of reddish, on solitary, terminal or axillary peduncles; calyx deeply 5-parted, the lobes narrow or often foli- aceous; corolla funnelform or salverform, the tube long and nearly or quite straight and sitting loosely in the calyx, the limb broad and normally 5-lobed, unequal or oblique and in some species obscurely 2-lipped; stamens 5, attached in the tube, one of them sometimes sterile; ovary small, 2-celled, the style slender, the stigma dilated and sometimes obscurely 2-lobed.—There are 12 or more species of Petunia, mostly natives of the southern part of S. Amer. One or two grow in Mex. and another (P. parviflora) is naturalized in the southern parts of the U. S., and is found frequently on ballast about seaports. The genus is closely allied to Salpiglos- sis, being distinguished by 5 perfect stamens, whereas that genus has 4 stamens and lvs. narrow or usually dentate or pinnatifid. Garden petunias are small soft plants of straggling or decumbent habit, pubescent and usually more or less sticky, with large showy flowers. The colors are white to light purple, not blue, clear red, nor yellow. They are properly perennial, but are treated as annuals in cultivation. The common kinds are rather weedy in habit, but their great profusion of bloom under all conditions makes them useful and popular. They are particularly useful for massing against shrubbery, for they make a florid undergrowth with almost no care. Some of the modern improved named varieties are very choice plants. Petunias emit a powerful fragrance at nightfall, and sphinx-moths visit them. The varieties of present-day gardens are considered to be hybrids and modifications of two-stem types. The types were white-flowered in one case and rose- violet in the other, and the flowers were small. In some of the garden strains, the flower is very broad and open, measuring 4 or 5 inches across. There are types with the flowers deeply fringed; others with star-like markings radiating from the throat and extending nearly or quite to the margin of the limb; others with full double flowers. Petunias should begin to bloom about two or two and one-half months after sowing in the open and continue profusely till killed by hard frost (the first light frosts usually do not injure them). The plants are at first erect, but soon begin to sprawl. The highest blooms of mature but sprawled plants will stand 18 to 24 inches above the ground. There are very dwarf and compact kinds, but they are not much seen in this country. Varieties or strains naturally fall into the small- flowered and large-flowered classes. The former are singles and are mostly used for bedding or massing. Some of the small lilac-limbed kinds are apparently very closely related to the stem-species, P. violacea, possibly direct derivatives of it. Countess of Ellesmere, Rosy Morn, and similar ones are among the best rosy or pink kinds for edgings and hanging-baskets and window- boxes. Large-flowered petunias are double or single, fringed, ruffled, fluted, and otherwise modified, some of them having deep velvety colors of great richness and flowers of much substance. There are marbled, spotted, and penciled flowers among them. Double forms are produced by crossing the most double flowers that are capable of producing good pollen on the best single strains. Only a part of the seedlings produce doubles, but all the others are likely to produce superior semidouble and single forms. Single flowers carefully pollinated from double flowers will produce seed which will average 25 per cent doubles, and single flowers bearing petaloid anthers similarly pollinated will give an average as high as 40 per cent doubles. The weaker seedlings are most likely to give full double flowers. Petunias thrive on both ordinary and rich soil, blooming well on land too rich for other plants, and some of the bedding and small kinds doing well even on poor soil with plenty of moisture. They are sun-loving plants, although they bloom well in partial shade. The culture is simple and easy. Seeds may be sown directly in the open, or the plants may be started in flats or pots indoors for early results. The plants are tender and therefore should not be trusted in the open until settled weather comes. The high-bred types require more care in the growing. They would best be started indoors, and be given the choicest positions in the open garden. Extra care should be given to the germination, for every seed that is lost may mean the loss of a form unlike any other; for these high-class petunias are not fixed into definite seed-varieties to any extent. Usually the weakest plants in the lot of seedlings will produce the choicest results among the high-bred single and double strains, the strongest seedlings tending to make weedy plants. Transplanting is recommended for the high- bred fringed and double strains, as well as for early bloom. The seeds are small and should be covered lightly in well-pulverized soil. On ordinary soil, petunias may be thinned or transplanted to 10 or 12 inches apart each way; but on fertile soil, and particularly with the larger-growing forms, the distance may be as much as 15 to 18 inches. Young petunia plants are very susceptible to frost. It is well to pull out some of the least desirable plants as they grow and begin to crowd. The stronger common strains of petunia are likely to self-sow or volunteer (come up themselves in the spring from seed). Fancy kinds are sometimes propagated by cuttings or slips from plants carried over winter, after the manner of geraniums. The best double strains particularly are often perpetuated by cuttings. There are no special insects or diseases attacking the petunia. Winter bloom is easy to secure from petunias under glass. Best, or at least quickest, results are secured from cuttings; these may be taken from good shoots in late September or early October from selected outdoor plants, and bloom should be secured by February 1. If plants are grown from seeds, the sowing should take place in late summer, for seedlings grow slowly in the short days of fall and winter; the seedlings should be handled in pots. Sometimes old plants that are not spent are lifted in the fall and cut back, and the new growth will give good winter bloom. Petunias under glass require cool treatment, a night temperature of 45° to 50° suiting them well. A somewhat warmer treatment than that given carnations may be expected to produce satisfactory results. The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.

Cultivation

When growing petunias, it's best to leave them in full sunlight and only water them when their soil is dry to the touch. Although generally grown as annuals (at least in temperate areas), they are perennial in warm climates (roughly zone 9 or warmer).

Propagation

Petunias are generally insect pollinated with the exception of P. exserta, which is a rare, bird pollinated species. Most petunias are diploid with 14 or 18 chromosomes and are interfertile with other petunia species.

Pests and diseases

The foliage of Petunias are sometimes eaten by the larvae of some Lepidoptera species including Dot Moth and Hummingbird hawk moth.

Species

• Petunia axillaris
• Petunia integrifolia
• Petunia x hybrida Wave Pink Hybrid
• Petunia grandiflora Park's Whopper Hybrid Burgundy

References

• Flora: The Gardener's Bible, by Sean Hogan. Global Book Publishing, 2003. ISBN 0881926248
• American Horticultural Society: A-Z Encyclopedia of Garden Plants, by Christopher Brickell, Judith D. Zuk. 1996. ISBN 0789419432