Giant Saguaro desert cactus – facts and photos

Within Arizona’s Tucson Basin is The Saguaro National Park.  This park provides the ideal conditions for sustaining dense stands of the famous saguaro cactus.

saguaro cactus at The Saguaro National Park
saguaro cactus at The Saguaro National Park in Tucson

**The most important factors for growth are water and temperature. If the elevation is too high, the cold weather and frost can kill the saguaro. Although the Sonoran Desert experiences both winter and summer rains, studies show that the Saguaro cactus obtains most of its moisture during the summer monsoon season.

Saguaro National Park
saguaro cactus in Arizona

There are dozens of varieties of cacti;  short, tall, stout, delicate but none quite as magnificent as the Giant Saguaro cactus.

Quick Saguaro Facts:

  1. Saguaros have one deep tap-root but most of this cactus’ roots are 4-6 inches deep and span out as far as the desert plant is tall.
  2. The saguaro is the largest cactus in the US.
  3. After the saguaro dies its woody ribs can be used to build roofs, fences, and parts of furniture.
  4. The Giant Saguaro can live to be 200 years old.

In the Sonoran desert the saguaro cactus has a boundless variety of towering armed shapes.

the saguaro cactus in arizona
the saguaro cactus species in AZ

Water makes up 75 to 95 percent of the saguaro cactus’ weight.  During periods of drought the pleats of the saguaro cactus contract.  During Arizona rains the saguaro expands as it soaks up moisture.

saguaro cactus with fruit
saguaro cactus close up

Saguaros, like many desert cacti, grow excruciatingly slow.  Arizona cactus experts estimate that a forty-foot tall saguaro is about 150 years old.  Arm buds begin to appear when the saguaro is 75 years old.

the saguaro arms
the saguaro arm buds

Many saguaros now standing in cactus forests germinated in the mid-1800s !!

saguaro cacti over 100 years old
saguaro cacti over 100 years old

To survive their early years, saguaro seedlings must be sheltered from the elements, whether it be under the canopy of other plants or in the crevices of rocky outcrops. Saguaro seeds can be deposited in droppings of birds roosting on branches of shrubs and trees.

nurse tree
young saguaro cacti under a nurse tree

Lightning, powerful winds, harsh winter freezes and the rotting of dead tissue kill saguaros.  Their woody ribs stay on the desert floor until they are consumed by termites or decay and return to the soil.

dead saguaro cactus wood
woody spine of the dead saguaro cactus

This cactus species is not currently listed as threatened or endangered. Arizona has strict regulations about the harvesting, collection or destruction of the saguaro cactus.

You can find the majestic giant cactus in southern Arizona and western Sonora, Mexica.

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The best time to see the Saguaro cactus bloom

The saguaro, Carnegiea gigantea, is the largest cactus in the United States and native to Arizona. In 1931 the opulent white blossom of the Saguaro Cactus was designated as Arizona’s state flower. The best time of year to see these cactus bloom is April through June.

flower buds on desert cactus
large white flowers on the saguaro cactus

The Saguaro cacti mainly grow in the Sonoran Desert of Arizona.  When a Saguaro cactus reaches 35 years of age it begins to produce blossoms.  Amassed near the ends of the branches, the green buds bloom into milky-white flowers. The Saguaro flower blooms after sunset and last only one day.

Arizona state flower
Saguaro Cactus Blossom

At the top of the flower tube is a compact group of yellow stamens. The saguaro cactus has more stamen on its flower than any other cactus.  If conditions have been favorable for the Saguaro you could see hundreds of blossoms on a cactus.

Arizona state flower
yellow stamen inside the Saguaro Cactus flower

Pollinators like birds, insects, and bats are attracted to the nectar that collects at the bottom of the flower’s 4 inch tube.  A Saguaro blossom can only be fertilized by cross-pollination.

Tucson Arizona saguaro blossom
yellow stamen inside the creamy white Saguaro flower

Only a few Saguaro flowers bloom each night and close by late morning; thus, giving a greater opportunity for pollination.

Arizona state flowers
white cactus flower attracts birds

This elegant desert pageant occurs for about 2 months. From living in this area, we have to say it is hard to decide the exact dates but end of April to mid June would be notable.

 Gila woodpecker inside the saguaro flower

bird pollinating the Saguaro cactus blossom

pollinated Saguaro Cactus red fruit
Red fruit of the Saguaro Cactus

Pollinated flowers form a vivid red fruit filled with thousands of black seeds.  The fruit is eaten and digested through which its dispersed throughout the desert.

The Saguaro National Park

While traveling Arizona we stopped at Saguaro National Park, in Tucson.  The park is located in the Sonoran Desert.

Saguaro National Park in AZ
Saguaro National Park in AZ

The giant cacti, called Saguaros, are protected and preserved within the park.

The saguaro cactus in the Sonoran Desert
The saguaro cactus in the Sonoran Desert

After a single rainfall, Saguaros can soak up to 200 gallons of water through their huge network of roots that lay just 4-6 inches below the desert surface. That is enough water to last this giant cactus an entire year!

the saguaro expands with water
the saguaro expands with water

A saguaro expands like an accordion when it absorbs water which can increase its weight by up to a ton.

saguaro cactus white flowers in bloom
saguaro cactus white flowers in bloom

In 1931, The Saguaro’s Blossom became the Arizona State Flower.

The Saguaro Cactus blooms April through June. Its flowers are creamy white and numerous. Up to a hundred flowers can bloom on one Saguaro Cactus!

Saguaro Cactus Flowers
Saguaro Cactus fruits and blooms

The saguaro blossom opens after sunset and by the next afternoon the flower is wilted. The white cactus flower repeats itself night after night.   During the few hours the saguaro flower is open birds, bats, and  honeybees pollinate them.

saguaro red fruit
saguaro red fruit

Later in the summer, the cactus flowers that were pollinated will become red-fleshed saguaro fruits that are enjoyed by the local bird population. The saguaro cactus is also known as the pitahaya, sahuara and giant cactus.

Saguaro National Park
Saguaro National Park
trails at Saguaro National Park
trails at Saguaro National Park
nursing trees for saguaros
Palo Verde and Mesquite Trees are shelter for young Saguaros
nursing tree for saguaro cactus
nursing trees provide nitrogen for cactus

The Saguaro often begins life with a nurse tree or shrub which can provide shade and moisture for the germination of life. This Saguaro grows slowly — only about an inch a year — eventually becoming very tall;  reaching heights of 50 feet.  The largest saguaro cacti, with more than 5 arms, are approximately 200 years old.