Tucson Mountain District Roads Closed Due to Flash Flooding
Several interior roads, including the scenic loop, are closed in Tucson Mountain District (west) due to severe storms and flash flooding during the week of July 6. Crews are working to repair the roads and expect to reopen on Friday, July 11. More »
Fire Restrictions in effect for Saguaro National Park
Due to fire danger in Southern Arizona, Saguaro National Park will implement fire restrictions beginning Thursday, June 5, 2014. Restrictions prohibit campfires, charcoal, coal or wood stove fires, fireworks, and smoking except within enclosed vehicles. More »
How Saguaros Grow
Saguaros are a very slow growing cactus. In Saguaro National Park, studies indicate that a saguaro grows between 1 and 1.5 inches in the first eight years of its life.
These tiny, young saguaros are very hard to find as they grow under the protection of a "nurse tree", most often a palo verde, ironwood or mesquite tree. As the saguaro continues to grow, its much older nurse tree may die. Some scientists believe that competition from the saguaro may lead to the death of the nurse tree by taking water and nutrients from the soil in the immediate area.
As a saguaro begins to age, growth rates vary depending on climate, precipitation and location. We do know that the period of greatest growth in a saguaro cactus is from unbranched to branched adult.
Here at Saguaro National Park, branches normally begin to appear when a saguaro reaches 50 to 70 years of age. In areas of lower precipitation, it may take up to 100 years before arms appear.
An adult saguaro is generally considered to be about 125 years of age. It may weigh 6 tons or more and be as tall as 50 feet. The average life span of a saguaro is probably 150 - 175 years of age. However, biologists believe that some plants may live over 200 years.
Did You Know?
The average life span of a saguaro cactus is 150 years, but some plants may live more than 200 years. A 20 foot tall saguaro weighs approximately 1 ton (2000 pounds).