Most garden plants are either annuals that bloom for one season only, or perennials that blossom once a year for multiple years. It is possible, though, to find flowers that bloom more than once a year. The specific plants that will blossom twice in your garden depend on your climate and growing conditions, but there are a few varieties that can generally be counted upon for biannual blooms.
Related to the rhododendron, the azalea is a flowering shrub known as the "royalty of the garden." Encore azaleas bloom more than once a year and grow best in U.S. Department of Agriculture planting zones 7 to 10, in slightly acidic soil. Encore azalea cultivars include Autumn Royalty, an azalea/rhododendron hybrid; Autumn Starlight, which has 3-inch white flowers that have pink freckles or stripes; and the Pink Craze, cold hardy, with light pink flowers.
Most orchid varieties bloom once a year, but the miniature cattelya orchid is notable for blooming twice -- other cattelyas also bloom twice depending on the variety and growth conditions. Speak with your seed supplier or garden expert to find out what will work in your own yard. Note also that other varieties might start blooming twice a year after they have had a few growths. The cattelya grows best in tropical climates.
Bearded irises are available in a range of colors, sizes -- under 8 inches to 42 inches tall -- and color patterns (including dark lower petals topped by lighter upper ones, and white petals with dark stippling). The climate needed for a bearded iris depends on the specific variety you are trying to grow, so check carefully with your plant supplier. Note that some varieties start to re-bloom only after a few years