Annuals:
Pro: Most bloom profusely all summer long. Because they live for only one season, they can afford to put all of their energy into producing abundant flowers throughout the growing season. Annual plants afford you the seasonal customization of your beds, pots and hanging baskets; They are floriferous, so they will brighten up mixed borders with non-stop color.
Con: If you grow lots of annual flowers, you are familiar with the annual chores necessary to maintain such beds: you purchase flower seedlings (or start your own), and plant them. You nurture them throughout the growing season, fertilize and water them; then, when the season’s over and the plants die, you pull them out. Next year, the cycle begins anew.
Perennials:
Pro: Perennial plants remain in the ground year after year. Once established, many perennials need minimal upkeep in the form of watering and fertilizing, since their roots are more far-ranging than annual plants’ roots. Many perennials spread readily, filling out garden spaces and providing more and more color each year.
Con: Since they live for many years, they must reserve energy to put into their root structure and cannot expend it all on blooming. Most perennials will bloom 3-4 weeks, although there are some that will produce flowers for up to 8-10 weeks.