Cacti are flowering plants, so every kind of cactus is capable of blooming when it is mature. Whether or not an individual cactus plant blooms depends on its age and the care it gets. Some cacti don't bloom until they are more than 30 years old. Others won't bloom, even if they are old enough, unless they get proper light conditions, watering and fertilization. This is especially true for potted cacti. Holiday cacti grown indoors, such as Christmas cactus, won't bloom unless they get long nights and short days.
Columnar Cacti
Tall-growing columnar cacti often take years before they bloom for the first time if grown from seed. If you root a branch from a mature, already-blooming columnar cactus, it will keep blooming after it is separated from the mother plant and rooted. However, some cacti, such as saguaro (Carnegiea gigantea), native to Arizona in U.S. Department of Agriculture plant hardiness zones 9 through 11, have branches that won't root, so saguaro has to be grown from seed, with a 40- to 55-year wait for the first flower. Some columnar cacti that produce flowers for the first time after 10 to 20 years and can live outdoors in USDA zones 9 through 11 are Peruvian apple cactus (Cereus peruvianus) with blue stems and large white night-blooming flowers, senita cactus (Lophocereus schottii) with gray-green stems and small pink flowers produced amid an area of dense shaggy spines, and Mexican fence post (Lemaireocereus marginatus) with bright green stems that have white-defined stem ridges and smaller white flowers. Columnar cacti are effective landscaping plants even without flowers.
Short-Stem Cacti
Short-columnar cacti with mature stems below 2 feet tall usually flower within five years from germination. Hedgehog cacti (Echinocereus spp.) are native to the United States and Mexico, and make mounding clumps of many stems over time. Large pink, magenta or red flowers are abundant in spring. Depending on the species, hedgehog cactus grows in USDA zones 5 -- for red-flowered short claret cup (E. triglochidiatus var. coccineus) -- through 11. Easter lily cactus (Echinopsis oxygona and hybrids) are hardy in USDA zones 8 through 11. They produce huge funnel-shaped flowers in white, pink, lavender, magenta or red. For the size of the plant, peanut cactus (Echinopsis chamaecereus) produces large flowers. Stems 2/3 inch long, covered with weak white spines, crawl along the ground and produce abundant bright orange flowers over 1 inch wide in spring. Peanut cactus