Annual wildflowers are the ones which grow quickly from seed, bloom usually for a long period (about two months, on average), and then die with the first hard frost. This means annual wildflowers live only one growing season. They are propagated by dropping their seeds as their flowers fade. This tells you that if you know of an annual that “came back” for a second year after a winter, it simply re-grew the second year from seed it produced the year before. This is called “self-sowing, and usually happens only when annual seed falls on bare ground. Most wild annuals are native to open spaces, rather than areas that are, or were originally, wooded. Popular wild annuals are the European red poppy and North America’s plains coreopsis.
Perennial wildflowers are the ones that “come back” each year from the same roots, forming larger and larger clumps with more and more flowers as they age. From seed, they germinate more slowly than most annuals, and make minor above-ground growth during their first growing season. Bloom usually begins their second growing season, and a perennial’s season of bloom is usually much shorter than that of an annual. (The average perennial blooms for about two weeks.) Examples of perennials are common daisies, purple coneflower, St. Johnswort, and the goldenrods. Some perennials live to return year after year for decades or even centuries. Others are what botanists call “short-lived”, which usually means the plant persists for less than five years.
The third and smallest group of wildflowers are the biennials. These plants have a two-year life-cycle. Like perennials, they normally do not bloom their first year, but bloom and seed profusely– for a comparatively long period– their second. Common examples of biennials are our common roadside weed, Queen Anne’s lace, and one of North America’s most popular native flowers, the black-eyed Susan.