City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/75614
The browning at the root flare of this saguaro is indicative of matu- rity and onset of senescence. Photo by Juan Barba In a recent large-scale study by the Arizona Department of Transportation (AZ DOT) of saguaro survival, the greatest single indicator of long-term survival was stem height. When transplanted prior to flowering or putting on arms, saguaros are still young, only 50 to 70 years old. At this age, they are still exhibiting youthful vigor and can recover from transplant stress much easier. They can be moved with much greater success in the 6- feet-tall (1.8 m) range than in the 12- to 20-feet (3.7 to 6.1 m) tall range of the multi-armed, larger saguaros. The above-ground size of the saguaro can greatly affect the depth at which they are planted. A 6 foot saguaro, called a "spear" in the trade, can be carried to the planting site by three or four workers and when erected, will resist windthrow better when planted at or near grade than those two to four times that height. The AZ DOT study found the survival rate plummeted when the salvaged roots were planted below grade; even 6 inches (15 cm) deep began to have a negative influence on the eventual survival of the cactus. Cactus movers know that transplanted saguaros plant- ed deep enough to stay upright in windstorms will live long past their guarantee, and so, unfortunately, many are installed 12 inches (30 cm) or more below their original grade. That mature saguaro will be unable to develop new roots and will need to be removed in a handful of years. Remember, the vast majority of roots are only 4 inches (10 cm) deep. Saguaros with arms, especially arms of 3 to 5 feet (.91 to 1.5 m), are more desirable to buyers if they are try- ing to make an immediate statement. A transplanted 12 This saguaro "spear" has been planted reasonably close to origi- nal grade, probably 3 to 4 inches (7.6 to 10.2 cm) deep. Photo by Juan Barba City Trees