Tips For Caring For Saguaro Cactus
By: Bonnie L. Grant, Certified Urban Agriculturist
Saguaro cactus (Carnegiea gigantea) blossoms are the state flower of Arizona. The cactus is a very slow growing plant, which may add only 1 to 1 ½ inches (2.5-3 cm.) in the first eight years of life. The Saguaro grows arms or lateral stems but it may take up to 75 years to produce the first one. Saguaro are very long lived and many found in the desert are 175 years old. It is likely that rather than growing Saguaro cactus in the home garden, you may find yourself the becoming owner of a well established Saguaro cactus when you buy a new home or build a home on land where Saguaro cactus already grow.
Saguaro Cactus Characteristics
Saguaro have barrel-shaped bodies with peripheral stems called arms. The exterior of the trunk is pleated due to the way it grows. The pleats expand, allowing the cactus to gather extra water in the rainy season and storing it in its tissues. An adult cactus may weigh six tons or more when filled with water and requires a strong internal support skeleton of connected ribs. A young growing Saguaro cactus may only be a few inches (8 cm.) tall as ten year old plants and take decades to resemble the adults.
Where Do Saguaro Cactus Grow?
These cacti are native to and only grow in the Sonoran Desert. Saguaro are not found in the entire desert but only in areas that don’t freeze and at certain elevations. The freezing point is one of the most important considerations of where do Saguaro cactus grow. The cactus plants are found from sea level up to 4,000 feet (1,219 m.). If they are growing above 4,000 feet (1,219 m.), the plants survive only on south slopes where there are fewer freezes of shorter duration. Saguaro cactus plants are important parts of the desert ecology, both as habitat and as food.
Saguaro Cactus Care
It is not legal to procure a Saguaro cactus for home cultivation by digging it out of the desert. Beyond that, mature Saguaro cactus plants almost always die when transplanted.
Saguaro cactus babies grow under the protection of nurse trees. The cactus will continue to grow and often its nurse tree will expire. It is thought the cactus may cause the nurse tree to die by competing for resources. The nurse trees provide Saguaro cactus babies with shelter from the harsh rays of the sun and dispersing moisture from evaporation.
Saguaro cactus needs to grow in well-drained grit and receive low levels of water, with the soil drying out completely between irrigation. Annually fertilizing with cactus food in spring will help the plant complete its growth cycle.
There are common cactus pests such as scale and mealybugs, that will require manual or chemical controls.
Saguaro Cactus Blossoms
Saguaro cactus are slow to develop and may be 35 years of age or more before they produce the first flower. The flowers bloom in May until June and are a creamy white color and about 3 inches (8 cm.) across. The Saguaro cactus blossoms only open at night and close in the day, which means they are pollinated by moths, bats, and other nocturnal creatures. The flowers are generally located at the end of the arms but may occasionally decorate the sides of the cactus.
This article was last updated on
Were you aware that saguaros are black market commodities? Here’re some other cool cactus facts.Saguaro cactus, Saguaro National Park (Rincon Mountain District), Arizona. Image: SonoranDesertNPS/flickr/CC BY-2.0
Science Friday’s broadcast in Phoenix, Arizona, got us thinking more about a popular desert fixture—the saguaro cactus, a huge plant with a big appetite for water. Did you know that…
- 1 Description
- 1.1 Ribs
- 1.2 Spines
- 1.3 Flowers
- 1.4 Fruit
- 1.5 Genome
- 2 Taxonomy
- 3 Distribution and habitat
- 4 Ecology
- 4.1 As food
- 4.2 Nests
- 5 Conservation
- 6 Uses
- 6.1 Ethnobotany
- 7 Culture
- 8 Gallery
- 9 References
- 9.1 Further reading
- 10 External links
The saguaro is a columnar cactus that grows notable branches, usually referred to as arms. As many as 49 arms may grow on one plant. Saguaros grow from 3–16 m (10–52 ft) tall, and up to 75 cm (30 in) in diameter. They are slow growing, but routinely live 150 to 200 years. They are the largest cactus in the United States.  
The growth rate of this cactus is strongly dependent on precipitation saguaros in drier western Arizona grow only half as fast as those in and around Tucson. Saguaros grow slowly from seed, and may be only 6.4 mm ( 1 ⁄4 in) tall after two years.  Cuttings rarely root, and when they do, they do not go through the juvenile growth phase, which gives a different appearance.  Since 2014, [update] the National Register of Champion Trees listed the largest known living saguaro in the United States in Maricopa County, Arizona, measuring 13.8 m (45 ft 3 in) high with a girth of 3.1 m (10 ft 2 in) it has an estimated age of 200 years and survived damage in the 2005 Cave Creek Complex Fire.   The tallest saguaro ever measured was an armless specimen found near Cave Creek, Arizona. It was 78 ft (23.8 m) in height before it was toppled in 1986 by a windstorm.  Saguaros are stem succulents and can hold large amounts of water when rain is plentiful and the saguaro is fully hydrated, it can weigh between 1,500 and 2,200 kg (3,200 and 4,800 lb).  
|0.5 feet (0.15 m)||9|
|1.0 foot (0.30 m)||13|
|5.0 feet (1.5 m)||27|
|10.0 feet (3.0 m)||41|
|20.0 feet (6.1 m)||83|
|25.0 feet (7.6 m)||107|
|30.0 feet (9.1 m)||131|
|35.0 feet (10.7 m)||157|
Saguaros have a very large root network that can extend up to 30 m (100 ft), and long taproots of up to 1 m (3 ft 3 in) deep. 
Saguaros may take between 20 and 50 years to reach a height of 1 m (3 ft 3 in). 
As a cactus, it uses crassulacean acid metabolism photosynthesis, which confers high levels of water-use efficiency. This allows the saguaro to only transpire at night, minimizing daytime water loss. 
A saguaro without arms is called a "spear". 
Some saguaros grow in rare formations called a cristate, or "crested" saguaro. This growth formation is believed to be found in one in roughly 10,000 saguaros, with 2743 known crested saguaros documented.  The crest formation, caused by fasciation, creates a seam of abnormal growth along the top or top of the arm of the saguaro. 
Inside the saguaro, many "ribs" of wood form something like a skeleton, with the individual ribs being as long as the cactus itself and up to a few centimeters in diameter. The rib wood itself is also relatively dense, with dry ribs having a solid density around 430 kg/m 3 (27 lb/cu ft), which made the ribs useful to indigenous peoples as a building material. While the ribs of dead plants are not protected by the Arizona native plant law, the Arizona Department of Agriculture has released a memo discussing when written permission is needed before harvesting them because of the importance of the decomposition of cactus remains in maintaining desert soil fertility. 
The composition of the ribs is similar to that of hardwoods.  : 326
The spines on a saguaro are extremely sharp and can grow to 7 cm (3 in) long,  and up to 1 mm ( 1 ⁄32 in) per day. When held up to the light or bisected, alternating light and dark bands transverse to the long axis of spines are visible. These bands have been correlated to daily growth. In columnar cacti, spines almost always grow in areoles that originate at the apex of the plant. A spine stops growing in its first season. Areoles are moved to the side and the apex continues to grow upward. Thus, older spines are toward the base of a columnar cactus and newer spines are near the apex. Studies are underway [ when? ] [ by whom? ] to examine the relationship of carbon and oxygen isotope ratios in the tissues of spines of an individual to its climate and photosynthetic history (acanthochronology). 
The spines may cause significant injury to animals one paper reported that a bighorn sheep skull had been penetrated by a saguaro spine after the sheep collided with a saguaro.  They can also cause severe injury to humans, being as sharp and nearly as strong as steel needles. Their long, unbarbed nature means that partially embedded spines can be easily removed, but their relative length can complicate injuries. The spines can puncture deeply, and if broken off, can leave splinters of spine deep in the tissue that can be difficult to remove. Fully embedded spikes are also difficult to remove. Such injuries do not usually result in infection, though, as the cactus spines are generally aseptic. However, spines that remain embedded may cause inflammatory granuloma. 
The white, waxy flowers appear in April through June, opening well after sunset and closing in midafternoon. They continue to produce nectar after sunrise.  Flowers are self-incompatible, thus requiring cross-pollination.  Large quantities of pollen are required for complete pollination because many ovules are present. This pollen is produced by the extremely numerous stamens, which in one notable case totaled 3,482 in a single flower.  A well-pollinated fruit contains several thousand tiny seeds. 
Pollination is considered relatively generalized in that multiple species can produce effective pollination when some populations are excluded. Main pollinators are honey bees, bats, and white-winged doves. In most, but not all studies, diurnal pollinators contributed more than nocturnal ones. Honey bees were the greatest contributors. Other diurnal pollinators are birds such as Costa's hummingbird, the black-chinned hummingbird, the broad-billed hummingbird, the hooded oriole, Scott's oriole, the Gila woodpecker, the gilded flicker, the verdin, and the house finch according to studies that examined the relative contributions of diurnal pollinators. 
The primary nocturnal pollinator is the lesser long-nosed bat, feeding on the nectar. Several floral characteristics are geared toward bat pollination (chiropterophily): nocturnal opening of the flowers, nocturnal maturation of pollen, very rich nectar, position high above ground, durable blooms that can withstand a bat's weight, and fragrance emitted at night. Claw marks on the flower indicate pollination by a bat. 
Flowers grow 8.6–12.4 cm (3.4–4.9 in) long, and are open for less than 24 hours. Since they form only at the top of the plant and the tips of branches, saguaros growing numerous branches is reproductively advantageous. Flowers open sequentially, with plants averaging four open flowers a day over a bloom period lasting a month.  In Southern Arizona, saguaros begin flowering around May 3 and peak on June 4.  A decline in bat populations causes more daytime flower openings, which favors other pollinators. 
The ruby red fruits are 6 to 9 cm ( 2 1 ⁄2 to 3 1 ⁄2 in) long and ripen in June, each containing around 2,000 seeds, plus sweet, fleshy connective tissue.  
The fruits are often out of reach and are harvested using a pole (made of two or three saguaro ribs) 4.5 to 9 m (15 to 30 ft) long, to the end of which cross-pieces, which can be made of saguaro rib, catclaw, or creosote bush, are attached. This pole is used to hook the fruits or knock them free. 
Saguaro seeds are small and short-lived. Although they germinate easily, predation and lack of moisture prevent all but about 1% of seeds from successful germination. Seeds must wait 12–14 months before germination lack of water during this period drastically reduces seedling survival. The existence of nurse plants is critical to seedling establishment.  Palo verde trees and triangle bursage represent important nurse species. They act by regulating temperature extremes, increasing soil nutrients, and reducing evapotranspiration, among others. While nurse plants reduce summer temperature maxima by as much as 18 °C (32 °F), they are more important in raising winter minimum temperatures – as extended frosts limit the range of saguaros. 
The saguaro genome is around 1 billion base pairs long.  Sequencing has revealed that the genome of the saguaro's chloroplast is the smallest known among nonparasitic flowering plants. Like several other highly specialized plant taxa, such as the carnivorous Genlisea and parasitic Cuscuta, the saguaro has lost the ndh plastid gene, which codes for production of NADPH dehydrogenase pathway, but unlike those taxa, the saguaro remains fully autotrophic i.e. it does not eat or steal part of its food. The saguaro is remarkable for the scale and completeness of gene loss essentially no traces of the 11 ndh genes remain in the plastid. The genes appear to have been copied to the nuclear DNA and mitochondrial DNA, but those copies are non-functional. How the saguaro thrives in a high stress environment without working copies of this fairly important gene remains unknown, but it is possible that the functions of the ndh genes have been taken on by another pathway. 
The saguaro is the only species in the monotypic genus Carnegiea.  The first description of the saguaro was made by William H. Emory in 1848, during his surveys along the pre-Gadsden Purchase United States-Mexican border.  This description allowed cactus expert George Engelmann to formally name it, during his work on the United States and Mexican Boundary Survey, published in 1859.  The next major taxonomic treatment came from The Cactaceae, the seminal work on cactus by Nathaniel Lord Britton and Joseph Nelson Rose. [ citation needed ]
What tribe the saguaro belongs to is a matter of taxonomic dispute. A molecular analysis of the cactus family in 2010 placed the saguaro in the Echinocereinae.  The ARS Germplasm Resources Information Network places it in the Echinocereeae. 
The generic name honors businessman and philanthropist Andrew Carnegie.  The specific epithet gigantea refers to its formidable size. 
Saguaros are endemic to the Sonoran Desert and are found only in western Sonora in Mexico and in southern Arizona in the US, although plants are occasionally found in southeastern California. Elevation is a limiting factor to its environment, as the saguaro is sensitive to extended frost or cold temperatures.  No confirmed specimens of wild saguaros have been found anywhere in New Mexico, Texas, Colorado, Utah, or Nevada, nor in the high deserts of northern Arizona.  The northern limits of their range are the Hualapai Mountains in Arizona.  They are the northernmost columnar cacti in the Americas.  : 320
The saguaro is a keystone species, and provides food, shelter, and protection to hundreds of other species. Every stage of the saguaro's life sustains a significant number of species, from seedling to after its death. 
As food Edit
The saguaro provides voluminous amounts of pollen, nectar, and fruits.  The fruits are eaten by the white-winged dove and ants, so that seeds rarely escape to germinate.  White-winged doves are important pollinators, visiting blooms more often than any other bird species. For desert white-winged doves, 60% or more of their diet is saguaro-based. Their breeding cycle coincides with that of the saguaro blooming. 
Gila woodpeckers and gilded flickers create holes in the cactus to make nests, which are later used by other birds, such as elf owls, purple martins, and house finches.      Flickers excavate larger holes higher on the stem compared to Gila woodpeckers. The resulting nest cavity is deep, and the parents and young are entirely hidden from view. The saguaro creates callus tissue on the wound. When the saguaro dies and its soft flesh rots, the callus remains as a so-called saguaro boot, which was used by natives for storage. 
Gila woodpeckers (Melanerpes uropygialis) create new nest holes each season rather than reuse the old ones, leaving convenient nest holes for other birds, such as elf owls, tyrant flycatchers, and wrens.  In recent years, early breeding, aggressive, non-native birds have taken over the nests to the detriment of elf owls that breed and nest later. [ citation needed ] In 2020, a bald eagle was found nesting in a saguaro for the first time since 1937.  
Harming or vandalizing a saguaro in any manner, such as shooting them (sometimes known as "cactus plugging")  is illegal by state law in Arizona. When houses or highways are built, special permits must be obtained to move or destroy any saguaro affected.  Exceptions to this general understanding exist for example, a private landowner whose property is 10 acres (4 hectares) or less, where the initial construction has already occurred, may remove a saguaro from the property.  This is common when the cactus falls over in a storm, its location interferes with a house addition, or it becomes a potential hazard to humans. 
In 1982, a man was killed after damaging a saguaro. David Grundman was shooting and poking at a saguaro cactus in an effort to make it fall. An arm of the cactus, weighing 230 kg (500 lb), fell onto him, crushing him and his car. The trunk of the cactus then also fell on him.   The Austin Lounge Lizards wrote the song "Saguaro" about this death. 
Contrary to published statements,  no law mandates prison sentences of 25 years for cutting a cactus down however, it is considered a class-four felony with a possible 3-year, 9-month maximum sentence. 
Invasive species, such as buffelgrass and Sahara mustard, pose significant threats to the Sonoran Desert ecosystem by increasing the rate of fires.  Buffelgrass outcompetes saguaros for water, and grows densely. It is also extremely flammable, but survives fire easily due to deep root systems.  Saguaros did not evolve in an environment with frequent fires, thus are not adapted to fire survival. Most Sonoran desert ecosystems have a fire return interval greater than 250 years buffelgrass thrives at fire return intervals of two to three years. This has led to the reshaping of the Sonoran Desert ecosystem and threatens the survival of the saguaro. 
Climate change will threaten saguaros and their ecosystems, as deserts are particularly susceptible to climate effects. Rising daytime and nighttime temperatures will reduce the water use efficiency of saguaros, forcing them to use more water and making them more likely to die during drought periods. 
The utility of the saguaro was well known to Native Americans such as the Tohono Oʼodham, Pima, and Seri peoples, who still use nearly every part of the plant.   The fruit and seeds are edible,  being consumed fresh and dried, and made it into preserves and drinks.  The Tohono O'odham use long sticks to harvest the fruits, which are then made into a variety of products including jams, syrups, and wine.  The Tohono O'odham begin their harvest in June. A pair of saguaro ribs, about 6 m (20 ft) long, is bundled together to make a harvesting tool called a kuibit. The Tohono O'odham traditionally reduce the freshly harvested fruit into a thick syrup through several hours of boiling, as the fresh fruit does not keep for long. Four kilograms (9 pounds) of fruit will yield about 1 liter ( 1 ⁄4 U.S. gallon) of syrup. Copious volumes of fruit are harvested an example harvest in 1929 yielded 45,000 kg (99,000 lb) among 600 families.  : 324–326
The seeds are ground into meal or eaten raw, but the raw seeds are mostly indigestible. They are also pressed for their oils. They also have minor use in the tanning of leather. In modern times, these uses have declined, and the seeds are now mainly used as chicken feed.  : 324
The ribs of the dead saguaro were used for construction and other purposes by Native Americans.  The Tohono O'odham use it for making fences and furniture. The ribs are also used as livestock fodder. 
A variety of alkaloids, including carnegine, gigantine, and salsolidine, make the stems quite bitter, and an unpalatable way to gain water.  : 323
Reports of saguaro use date back to the Coronado expeditions of 1540–1542, which noted its use in winemaking.  : 324
The old bird nests resist the elements and are gathered by Native Americans for use as storage vessels.  Cactus boots, excavated by gilded flickers and taken from dead saguaros, have been used by native peoples as water containers. 
The saguaro features prominently in indigenous folklore and religions.  : 320
Arizona made the saguaro blossom its territorial flower on March 13, 1901, and on March 16, 1931, it became the state flower. 
The saguaro is often used as an emblem in commercials and logos that attempt to convey a sense of the Southwest, even if the product has no connection to Arizona or the Sonoran Desert. For instance, no naturally occurring saguaros are found within 400 kilometers (250 miles) of El Paso, Texas, but the silhouette is found on the label of Old El Paso brand products.   Though the geographic anomaly has lessened in recent years, Western films once enthusiastically placed saguaros in the Monument Valley of Arizona, as well as New Mexico, Utah, and Texas. The Dallas, Texas-based band Reverend Horton Heat pokes fun at this phenomenon in their song "Ain't no Saguaro in Texas". 
Saguaro towering over a 1.8 m (6 ft) man
Mature five-armed in flower
Snow-covered saguaro near Tucson. Saguaros can survive a few hours of below-freezing temperatures
Saguaro Cactus: 20 Facts About This Amazing Arizona Cactus
Part of living in the Anthem and Phoenix areas is enjoying the unique variety of native plants. Of course, the most easily recognizable desert plants are different kinds of cactus, including the iconic saguaro (Carnegiea gigantea).
The saguaro’s tall stature and curved arms make it stand out, and the flowers it produces in the late spring and summer months are our state flower for a reason! If you’re lucky enough to have them on your property, you know that they need different care than your trees or flowers.
Here are some things you may not know about the saguaro cactus:
- Not all of them grow arms.
If well cared-for, they can live 150-200 years or more.
Saguaros have quite the system for getting water – they have one deep taproot that can extend into the ground about 3-5 feet deep, but the rest of the roots are only 4-6 inches into the ground so they are able to absorb rainwater.
When fully hydrated, saguaros can weigh 3,200-4,800 lbs.
A saguaro once killed a man in “self-defense.” Yes, really. A man was shooting at a saguaro with a shotgun, causing one of its arms to break off and fall, crushing him (Also, don’t shoot at saguaros. They’re protected).
Saguaros only grow about a foot every 10 years.
A ten-year-old saguaro may still be only an inch and a half tall! They are incredibly slow growers, particularly when young. This is one of the reasons they are so strictly protected by the state.
Those that do grow arms (branches) will begin to grow them at about 40-80 years of age or when they’re around 12 feet tall.
Saguaro growing in the home landscape, particularly one that receives supplemental irrigation, tend to put out arms at a younger age than those in the wild.
The ridges or pleats on a saguaro have many purposes. They allow the cactus to expand (up to 20-25%) so they can take in water, they provide shade for the cactus, and they act as a windbreak, allowing the saguaro to remain tall during after strong winds.
Some saguaros develop a strange fan-like structure at the top instead of the arms we’re used to seeing. These rare, crested forms are highly prized.
Saguaro cacti are heavily regulated by the state, so be careful before you move one, destroy one, dig one up, or add one to your property. You may need a tag, a permit, or to pay a fee. Learn more about protected Arizona Native Plants from the Arizona Department of Agriculture.
If you buy a saguaro, be sure it’s not “hot”! Make sure the seller has a tag/permit (if you don’t see it attached to the plant, ask to see it before buying). If not, the saguaro may be stolen (often, they’re dug up on public land or abandoned properties) and you could be responsible for hefty fines if you purchase it.
Because saguaro are so heavy, it’s best to hire a professional to move and plant it for you. There are companies that specialize in doing that. And if a larger one breaks, drops an arm, or falls over, you’ll also need a professional to remove the pieces. Not only are the pieces heavy, they’re covered in armor-piercing thorns!
When a saguaro is planted, it should face the same direction as before (often this is marked before it is uprooted). As with many Arizona cacti, the saguaro’s hide is 15% thicker on the south-facing side, protecting it from our harsh sun. If replanted facing another direction, the saguaro will suffer from sunburn.
The Arizona state flower is the saguaro bloom, which usually appears in late spring through early summer. The flowers open during the night and last until only the following afternoon, so there’s a limited time for pollinators to get to the flowers.
Saguaros rarely need to be watered and should survive on rainfall alone. If they receive too much water, they can rot and fall over.
Various types of animals nest in saguaros, which is why so many have holes. One of the most common birds that nest in saguaro is the Gila woodpecker. It carves out a cavity shaped somewhat like a boot but waits until the walls of the cavity dry before moving in.
While many people have tried to plant/grow saguaros elsewhere, they only grow in the Sonoran desert.
The saguaro cactus is named after Andrew Carnegie (the scientific name is Carnegiea gigantea).
For more on buying/selling/moving saguaros, see this article.
For an interesting and more detailed read about saguaros from a fellow Phoenician, check out this post.
Mexican Fence Post Cactus (Pachycereus marginatus)Zozulya / Getty Images
" data-caption="" data-expand="300" data-tracking-container="true" />
The Mexican fence post cactus (Pachycereus marginatus) is a stunning blue-green columnar cactus that can grow up to 20 feet tall at maturity. Fortunately, this species of cactus is relatively fast-growing, so you may be able to start with a smaller plant and wait for it to grow to a decent size if you wish.
- Light: Direct sun.
- Water: Minimal water, water once the soil is dry.
4. Give your cactus the sunlight they need
Light is a necessity when caring for cactus. Desert cacti love direct sunlight and would do with four hours a day of some direct sunlight. The tropical cacti such as Christmas cacti prefer partial shade. During winter, tropical cacti such as Rhipsalis would ideally need direct sunlight because that’s when they bloom. If possible, expose them to direct sunlight for their growth.
Get to know your cacti well and know what works for them.
For indoor cacti, to get adequate light, ensure they are 4 feet of the window if it faces the east or south. Keep rotating the plant because too much sunlight will make them turn yellow or white.
During winter and autumn, cacti will need temperatures of between 8-10°C. In summer and spring, even as they require proper ventilation, they can do with higher temperatures.
If you are growing your cactus indoors, it is important to rotate it preferably every month. This is because cacti will tend to grow towards the light. Rotation strikes a balanced growth. Rotate the pot a quarter turn.
Can using grow lights work?
In the case that you think you won’t be able to provide sufficient sunlight, you can buy grow lights.
Grow lights are artificial lamps designed to help with indoor plants that require light but is insufficient in the growth of plants.
A Russian botanist first discovered them.
We have three types of grow lights: light emitting diodes (LED), fluorescent lights, and high-pressure sodium (HPS) or high-intensity discharge (HID).
- Fluorescent lights are used to grow herbs and vegetables indoors.
- For the HPS, you need to place your cactus a distance away from them as they produce quite high amounts of heat. They also require you to invest heavily in setting them up and having a system that will manage the temperature.
- The LED is more efficient than the other two types, and the light is far more focused. There is also very minimal heat produced if any.
A grow light will be able to imitate sunlight, which will help the cactus during their growing stage and help them to bloom.