The saguaro cactus (Carnegeia gigantea) is a symbol of the American Southwest and a familiar sight in western-themed movies. Saguaros grow in the Sonoran Desert of Arizona and far western Mexico. According to the United States National Parks Service, this slow-growing cactus reaches a height of only 1 to 1 1/2 inches during its first eight years. After 50 years, a saguaro develops thick, upward-growing branches or arms. At age 35, white flowers appear at the end of the trunk, and later at the ends of the arms. These iconic plants grow up to 50 feet tall and live up to 200 years.
A saguaro needs a warm climate where temperatures remain above freezing. For this reason, saguaro cacti grow at elevations below 4,000 feet, or on south-facing slopes above 4,000 feet. Frosts can cause twisted arms, or cresting, in a mature saguaro. For the first 25 to 50 years of its life, a saguaro needs protection from extreme heat or cold from a nearby ironwood, mesquite or palo verde "nurse tree."
Although it thrives in the hot, sunny desert climate, a saguaro cactus needs protection from the harsh sunshine of its native habitat. As it matures, it develops a tough texture on its south and southwestern sides. After the nurse plant dies, the toughened texture provides sunburn protection. According to the University of Arizona Extension, you should transplant a saguaro so that it faces the same direction as it faced in its original location.
A saguaro cactus needs only 10 inches of rainfall each year. To collect water from rainfall, a saguaro's shallow root system extends outward as far as its height. It stores water in its pleated trunk and arms, and uses the stored water during dry periods. The University of Arizona Extension recommends watering a saguaro once a month for 30 minutes during the summer. Do not water during the winter, and do not plant a saguaro near plants that require frequent irrigation.
During the spring, each saguaro flower opens one night and permanently closes the next afternoon. For reproduction, the flowers need bats, bees, birds and other pollinators that are active during these hours. According to a January 2005 article in "Smithsonian Zoogoer," lesser long-nosed and long-tongued bats feed on nectar and pollinate the flowers at night, while birds and insects pollinate during the day. In the summer, birds and bats eat the fruit and disperse the seeds.
- United States of the Interior National Parks Service: The Saguaro Cactus
- University of Arizona Cooperative Extension: Moderation is the Key to Saguaro Care; Mindy Siverson and Annie Chiu
- Smithsonian Zoogoer: The Long Arm of the Saguaro; Alex Hawes; January 2005
- University of Arizona Cooperative Extension: Cactus Culture; Jeff Schalau; July 2002
- Photo Credit NA/AbleStock.com/Getty Images