What Abiotic Factors Does the Saguaro Cactus Need?

Distribution

• Visit Arizona or the very southeastern slice of California if you want to see saguaro cacti in the United States; it is only in these states that the saguaro finds the abiotic, or nonliving, factors that the succulent requires to thrive. All undomesticated saguaro cacti grow in the Sonoran Desert -- which continues from Arizona down into Mexico -- but even within this desert, their range is limited by sun, air temperature and precipitation.

Sun

• A saguaro cactus needs sun to thrive, and not just an occasional ray. The Tuscon, Arizona, area, where most of the U.S. saguaros are located, receives an annual average of more than 85 percent sunshine hours. This means that more than 85 percent of daylight hours are sunny, rather than cloudy or raining. In June, the sunshine hours percentage rockets to 96 percent, while the low for the year is in July, at 78 percent.

Temperature

• Saguaros require warm day temperatures with night lows consistently above freezing. While the range of these cacti extends from sea level to 4,000 feet, in high elevations they develop only on south-facing slopes where freezing temperatures are infrequent. Freezing maims or kills the saguaros. When exposed to a severe freeze, portions of the saguaro yellow and then die. Freezing temperatures also greatly reduce cacti fruit production, and thus limit the number of seeds the species produces.

Precipitation

• Every plant needs water, even desert-dwelling saguaros. Like most cacti, the saguaro has developed methods of capturing and storing the cyclic rain. The saguaro roots, radiating in all directions, remain only a few inches below the surface of the soil to take advantage of all precipitation. During heavy rains, the cactus absorbs maximum water. The pleated skin of the cactus expands like an accordion to store excess water. As the saguaro uses its water supply, the skin contracts.