Annual. Extra-large petunia flowers reach 4 inches across, are of the whitest white. The plants are robust for petunias as well, frequently exceeding 15 inches tall. The chaste white funnel-shaped blooms are often fringed along the margins, look like soft, pillowy clouds as they float above the velvety green foliage. A cheerful cornerstone to the summer garden! A favorite from the mid-20th century.