Petunias are flowering plants, mostly hybrids derived from South American species. They are widely used ornamental annuals, valued for their prolific blooming and vibrant display from spring until the first frost. Petunias have been heavily hybridized, resulting in a diverse array of flower shapes, sizes, and plant architectures.
The Signature Flower Structure and Colors
The petunia bloom is large and showy, forming a distinctive funnel or trumpet shape. The corolla, or fused petals, typically flares out from a narrow tube at the base, often displaying a soft, velvety texture. Most common varieties feature a single layer of five petals, but double-flowered cultivars also exist where the petals are densely layered and ruffled, creating a full, almost carnation-like appearance. The color spectrum is exceptionally broad, encompassing pure white, deep pinks, reds, purples, blues, yellows, and even near-black hues. Many cultivars display intricate patterns, such as starbursts radiating from the throat, contrasting veining across the petals, or picotee edges where the margin is outlined in a different color.
Foliage and Stem Characteristics
Petunia leaves are generally simple and ovate or elliptic in shape, with smooth, untoothed margins. The non-flowering parts of the petunia plant present a uniform appearance of soft, medium-green foliage and stems. A defining tactile feature of the petunia is the slightly sticky feel of its leaves and stems. This stickiness is caused by the presence of numerous glandular hairs covering the plant’s surfaces, which secrete a sap that serves as a natural defense mechanism against certain insects and pests. The stems themselves are herbaceous and non-woody, often having a round circumference with a light green or sometimes purplish-green tint.
Distinctions in Growth Habit and Size
Petunias are visually categorized by their overall architecture, which dictates their best use in a landscape or container. Upright or mounding varieties, such as the Grandiflora and Multiflora types, grow into dense, bushy mounds. These typically reach a height of 6 to 18 inches, forming a compact, rounded structure that is ideal for garden beds or mixed containers.
Conversely, spreading or trailing petunias, popularized by series like Wave and Supertunia, exhibit an aggressive, sprawling growth habit. These types remain low to the ground, often only about six inches tall, but can spread horizontally up to four feet or more in a single season. This trailing characteristic makes them effective for spilling over the edges of hanging baskets, window boxes, or retaining walls, creating a cascade of color.