Great stands of giant saguaro cactus dominate Saguaro National Park in this protected Sonoran Desert terrain. Saguaro National Park is located in separate park units on either side of Tucson, Arizona. These giant saguaros are unique to the Sonoran Desert. They sometimes reach a height of 50 feet here, amid a dramatic cactus forest which covers the valley floor and rises onto the slopes of the Rincon and West Tucson mountains.
This unique desert is home to the most recognizable cactus in the world, the majestic saguaro. Visitors of all ages are fascinated and enchanted by these desert giants, especially their many interesting and complex interrelationships with other desert life. Saguaro cacti provide their sweet fruits to hungry desert animals. They also provide homes to a variety of birds, such as the Harris’ hawk, Gila woodpecker and the tiny elf owl. Yet, the saguaro requires other desert plants for its very survival. During the first few years of a very long life, a young saguaro needs the shade and protection of a nurse plant such as the palo verde tree. With an average life span of 150 years, a mature saguaro may grow to a height of 50 feet and weigh over 10 tons.
While most visitors to Saguaro National Park choose a leisurely drive on one of our scenic loop drives, those eager for an escape from the rigors of city life often opt to explore the park on one of our many trails. With over 150 miles of hiking trails, ranging from flat and easy strolls in the Sonoran Desert to steep and rugged hikes into the Rincon Mountains, visitors of every ability have a place to get out of the car and explore.
Nature & Science
Ecology
The giant saguaro begins its life as a shiny black seed no bigger than a period on this page. But what it lacks in size it more than makes up for in numbers. One saguaro produces tens of thousands of seeds in one year and as many as 40 million in a lifetime of 175 to 200 years. But from the start the odds against survival are great. Out of all the seeds that one saguaro produces in its life, probably only one will live to adulthood.
Seeds and young saguaros have the best chance for survival if they are “cared for” by nurse trees such as paloverde and mesquite. Saguaro seedlings that grow under these sheltering plants are shaded from the desert’s intense sunlight, blanketed from winter cold and hidden from rodents, birds and other animals that eat them. Rocks provide similar protection for young saguaros. Saguaros do best on bajadas gently sloping outwash plains at the foot of desert mountains.
Growth of a Green Giant
A saguaro’s growth is extremely slow. Growth occurs in spurts, with most of it taking place in the summer rainy season each year. By the end of a year the saguaro seedling may measure only 1/4 inch. after 15 years, the saguaro may be barely one foot tall. By 50 years the saguaro can be as tall as seven feet. after about 75 years it may sprout its first branches, or “arms”. The branches begin as prickly balls, then extend out and upward. This is also the stage of life when the saguaro begins to flower and produce fruit and seed.
By 100 years, the saguaro may have reached 25 feet. Saguaros that live 150 years or more attain the grandest sizes, towering as high as 50 feet and and can weigh more than 8 tons dwarfing every other living thing in the desert. These are the largest cacti in the United States. Their huge bulk is supported by a strong but flexible cylinder-shaped framework of long woody ribs.
Death and Rebirth
Saguaros may die of old age, but they also die of other causes. Animals eat the seeds and seedlings, lightning and winds kill large saguaros and severe droughts weaken and kill all ages.
Where there is a balance of life and death, saguaro forests thrive. But in some forests in Saguaro National Park deaths have greatly outnumbered the growth of new young saguaros.
What has caused the decline in these areas Biologists believe killing freezes are the number one cause of saguaro deaths in the park. The saguaros here are at the extreme northern and eastern edge of their range, where the coldest winter temperatures most often occur.
Man, too, has played a part in the decline. Livestock grazing, which continued from the 1880′s until 1958, devastated some forests. Many seedlings were killed outright by trampling or were unable to find suitable places to grow because the ground had been compacted and nurse trees killed.
Today, with grazing eliminated, recovery appears to be underway in several areas, where thousands of young saguaros have taken hold and are thriving. Still, natural forces, vandalism and cactus rustling the theft of saguaros for use in landscaping continue to take a toll on the park’s saguaro forests.
Recreation
Numerous guided walks are offered at each visitor center. Published schedules of programs are available during the winter season. Special environmental education programs are frequently conducted for local school groups. Both districts have miles of trails for hiking and scenic loop drives. For more information on these trails stop at the visitor center.
Start a park visit by stopping at the visitor center for maps, information and suggestions. Most visitors enjoy the scenic drives, bird watching, photography, hiking and participating in guided walks.
Getting There
Saguaro East (also known as the Rincon Mountain District) may be reached from Tucson by traveling east on Broadway or Speedway to Freeman Rd; turn right to Old Spanish Trail; turn left. Look for signs to the park entrance. Saguaro West (also known as the Tucson Mountain District) may be reached from Tucson by following Speedway Road. west. Speedway becomes Gates Pass Rd; this road ends at Kinney Rd, where you turn right and continue to the park entrance.
Saguaro East and West are each about 15 miles from downtown Tucson. Both units are accessible via signed exits from Interstate 10.
Traveler Facts
Contact Information
Saguaro National Park – Headquarters and Rincon Mountain District
3693 South Old Spanish Trail
Tucson, AZ 85730-5601
Phone: 520-733-5153- or -
Saguaro National Park – Tucson Mountain District
2700 North Kinney Road
Tucson, AZ 85743
Phone: 520-733-5158
Operating Hours & Seasons
Both districts of Saguaro National Park are open daily from 7:00 a.m. to sunset. Visitor centers are open daily from 8:30 a.m. to 5:00 p.m. daily. Both Visitor Centers are closed on Christmas Day.
Permits
Backcountry camping is permitted in Saguaro East. The required free permit can be obtained at the visitor center.
Visitors Centers
Both units of Saguaro National Park have visitor centers which offer slide shows, museum displays, cactus gardens and a sales outlet.
Weather/Climate
Winters are spectacular in Saguaro National Park with mild warm days between 60 and 70 degrees F and cool nights averaging 40 degrees F.
Summers can be extremely hot, with daytime temperatures as high as 115 degrees F in the shade and evening lows in the 80′s.
Long hikes are not recommended in the summer. Even short hikes require lots of water, a hat and sunscreen.
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