|Photo by Deb Langeloh 8/28/2016|
No one likes to see a Saguaro (Carnegiea gigantea) in this position, but this one may have toppled because of the monsoon rains. Saguaros have shallow roots at all stages of their life cycle. Unlike many other tall-growing plants (like trees), saguaros have no tap root. Their roots do extend radially, about as far as the plant is tall, but the deepest main root is only about 2-feet under the soil. Their shallow roots allow saguaros to quickly and efficiently take in rain water, but the roots can't anchor the plant if it gets too heavy or if the ground becomes saturated and muddy.
Trying to re-root a fallen saguaro is almost always an exercise in futility, especially if the saguaro is more than a foot or two tall. The saguaro pictured above simply has too much mass; the broken roots wouldn't be able to sustain it. Unlike some other cactus, you can't grow a saguaro from a piece (say, an arm) that's broken off. Again, there's simply too much mass - and roots won't sprout from the piece, anyway.