Difference between Annual, Perennial, Biennial

Annuals:

Plants that perform their entire life cycle from seed to flower and to seed within a single growing season. All the roots, stems and leaves of the plant die in annually. End of the cycle after annual plants produce mature seeds, they die, having exhausted themselves from sprouting, growing foliage and flowers, and finally producing viable seed in just one growing season. The mother plant dies, the plant may have left hundreds to thousands, of seeds to carry on her legacy. For annual plants, one generation per year is the norm, so they have a life cycle of one growing season. For e.g Dianthus, poppy, zinnia, cosmos, are annual .

Biennials: 

Biennials are a unique group of plants that only produce leaves the first year and then flower, go to seed and die the second. Generally, the seed is started between May and June and plants are set out in late August to early September.Biennial plants complete their life cycle over two growing seasons. The first season they grow only foliage, commonly a low-growing rosette of leaves. The second growing season they form flowers and produce seeds; then, the mother plant dies. Common biennial flowers include foxgloves and Canterbury bells. But did you know that cabbage, kale, Brussels sprouts, carrots, and celery are also biennials? We usually harvest them in their first season of vegetative growth, so we never actually see the flowers.

Perennials: 

Perennials, on the other hand, live for three or more growing seasons. They can be planted from bulb or seed – often bulbs must be planted in the fall to produce spring-blooming plants.You can purchase young plants at a nursery to plant in the spring. Perennials generally have shorter blooming periods than annuals, so gardeners often pair them with perennials that bloom at other times to maintain constant colour from spring to autumn.

First season growth results in a small rosette of leaves near the soil surface. During the second season's growth stem elongation, flowering and seed formation occur followed by the entire plant's death.It grows from seeds and bulb, Perennial plants continue to grow and flower for more than two years—and many will live for decades.

As with annuals and biennials, perennials produce flowers that, if successfully pollinated, form seeds. The difference is that the mother plant doesn’t die after producing seed. If we define a life cycle as the time it takes a plant to go from seed to seed, you can see that perennials’ life cycles can vary widely. For many common perennials, completing a life cycle usually takes from two to perhaps five years or more, For example, if you plant a cone-flower seed, you’ll get only foliage the first few years, with flowers and seed coming in subsequent years. If the first seed is formed the third season, then we would say the plant has a three-year life cycle, from seed to seed.

The word perennial is commonly used to describe long-lived herbaceous plants—those with green, non-woody stems. In temperate regions, most perennials die back to the ground in the winter, then sprout from the roots or crowns in the spring. Woody plants like shrubs and trees are also perennials, in that they grow for many years. However, in common usage, a distinction is made between woody and non-woody perennials. The word perennial is reserved for herbaceous, non-woody plants. Woody plants whose above ground parts persist through the winter are categorized as shrubs, trees, or woody vines.

Rose, Hibiscus