A petunia is a type of garden plant with pink, white, or purple flowers shaped like short, wide cones. a garden plant which has pink, purple, or white trumpet -shaped flowers (from early petun , from petyn). Any of many species of flowering plants in the genus Petunia, in the nightshade family, which originated in South America. The innumerable varieties of showy, trumpet-shaped flowers are immensely popular. There are two types: the compact, erect sort seen in summer garden beds, and the sprawling, long-stemmed sort seen in hanging baskets and window boxes. From early summer until frost, petunias bloom profusely with single or double blossoms; crisped, fringed, or ruffled flowers; and spectacular hues from pure white to deep crimson or purple, speckled or veined in contrasting colours. Leaves are soft, flabby, and covered with fine, sticky hairs. Technically perennials, petunias are most often grown as annuals