The saguaro will the grow many years as a straight pole. A few decades later the first arms might appear. A mature, multi armed saguaro might live several centuries. Frost, lightning and man are the primary dangers to a mature saguaro. The saguaro grows only at the tip of the stem or arm, if this tip is killed by frost or lightning that stem will stop growing, though more branches usually sprout when this happens.
Many saguaros show extensive scars from life in the desert.
The Gila woodpecker and Northern Flicker will carve cavities in the sides that quickly scar over and do no real damage. The resulting cavity can be over 20 degrees cooler than the surrounding air providing an excellent nest for the woodpecker or several other species that use abandoned woodpecker nests. The saguaro also provides the best perch around for many species including hawks. The saguaro flowers in May to June after most other desert flowers when the summer heat really begins. The primary pollinators of these night opening flowers are bats that migrate through the area, though insects and birds also visit the flowers.