The flower of the saguaro is Arizona's state flower.
When a saguaro is about eighteen to twenty feet tall (around sixty years old), it may begin to sprout arms. It also begins blooming about that time. Birds, particularly the Gila woodpecker, make holes in maturing saguaros. The saguaro is, after all, the tallest "tree" in the desert. The bird holes do not impair the plant's health.
WATERING: The only care which a saguaro needs to remain healthy is the proper amount of water. Saguaros which have been transplanted or those growing where construction altered their immediate environment may need supplemental water during long droughts or periods of intense heat. Watch the ribs: if they are close together, with a deep recess, or the plant begins to look thin, it needs water. Water a saguaro with a slow trickle away from the base of the plant. Dig a shallow trench around the plant or use a soaker ring to deliver the water on all sides, although that is not imperative. A saguaro's roots extend just under the surface of the soil in a circle about as wide as the cactus is tall. When rain falls or supplemental water is offered, the saguaro quickly grows tiny rootlets to absorb all the moisture it can. It will take about five days for the water to be absorbed and move up the body of the plant. Repeated waterings may be necessary to encourage sufficient root growth. Avoid allowing water to puddle around the base of the plant. The plant's water-absorbing roots are located away from the trunk and puddled water may encourage rot near the base.
Bacterial Necrosis (rot)
When the tissues of a saguaro's body are injured by physical damage, freezing weather, water deficiency, heat stress, or sunburn, bacteria can enter, causing the tissues to rot. The infection spreads quickly and is the main cause of death of saguaros. In cases when rot is detected early, the plant may be saved by cutting out the diseased tissue (it will be discolored and mushy), wiping the area with a solution of bleach in water (one part bleach to nine parts water) and leaving the hole to dry and heal in the fresh air and sunlight. The most obvious sign of rot is black, smelly ooze emerging from the cactus. If the rot is near the surface and in a localized area, the plant can likely be saved. If the rot is coming from deep within the plant's body, or occurs near the tips, the plant's chances for survival are slim.
Another sign that rot is present is when the plant begins to lean. Leaning can be caused by the erosion of soil around the plant's roots, but it is more likely that rot is destroying the inner structure of the cactus. A leaning cactus will eventually fall so immediate action is required to remove the plant to prevent serious inhury or property damage when it collapses. If nothing is threatened by the fall of the cactus, allowing it to remain where it falls makes an interesting feature in the home landscape. Saguaros are heavy--large, old plants can weigh up to 2 tons--take great care around a leaning saguaro, and don't stand near it, or push it.
