Last updated on August 25th, 2023 at 11:45 am
The saguaro cactus, also known as Carnegiea gigantea, is native to the Sonoran Desert in the Southwestern United States and northwestern Mexico.
Carnegiea gigantea lives only in the Sonoran Desert of the Southwestern United States and northwestern Mexico. It’s easily recognized by its massive size (the largest specimens can grow to 40 feet high), armlike branches, and the fact that it’s the namesake plant of Arizona’s Tucson and Maricopa County, as well as Saguaro National Park.
The Saguaro cactus has become iconic in Arizona’s wild desert southwest and one of the most easily recognizable symbols of the United States itself.
The cactus can grow up to 50 feet tall, but rarely reaches its full potential height due to grazing and other threats from man and nature alike.
Origin and distribution
Saguaro cactus is native to arid regions of western North America, from northern Sonora, Mexico, and extreme southwestern Arizona in the U.S., south through Baja California and most of western, central, and southern Arizona. The saguaro’s range extends into northern Sinaloa in Mexico.
It is found primarily on desert plains and slopes at low to middle elevations below 1,500 feet. Saguaros like well-drained soil with a pH between 6.0 and 7.5. They can grow in pure sand or rocky terrain; however, they need abundant groundwater near the surface.
They can grow from sea level to about 6000 ft in elevation but not any higher. They cannot survive freezing temperatures so it’s advised that you leave your cacti outside year-round where they are hardy!
Saguaro cactus propagation
Saguaro cactus are propagated from seeds or cuttings. The seeds need to be kept cold at around 55 degrees Fahrenheit in order to germinate. They can take anywhere from three weeks to eight months to sprout, so patience is necessary. Seeds should not be refrigerated with wet peat moss; rather, sterile potting soil should be used. After planting the seedling, it needs plenty of sun and water for about a year before it becomes established.
When a saguaro’s roots run out of space, they grow up and start growing branches. Cuttings will also grow new plants but they will only produce flowers if cross-pollinated by another saguaro cactus species within three years of taking the cutting.
There is no scientific consensus on how long these plants live. Some believe that they may live as long as 200 years while others say that after 20 years, some parts of the plant die off while other parts continue to thrive until they finally succumb to disease or weather.
Saguaro cactus care information
Saguaro cactus need very little care. They are drought-tolerant and even water will not hurt them, but they do prefer well-drained soil with a neutral pH, like regular potting soil.
If you live in an area where freezing temperatures occur, protect your saguaro from frostbite by covering it with a thick layer of mulch or fabric. Leave about 4 inches between each cactus for airflow; be careful not to plant them too close together!
Light requirement
Saguaro cactus need at least six hours of light each day for adequate growth. The more sun exposure they get, the bigger and faster they’ll grow. Be sure to place your saguaros in an area that receives plenty of sunlight if you want them to thrive. Otherwise, they’ll just shrivel up and die over time.
One interesting fact about these cacti is that their branches grow upward as opposed to outwards like most other plants. They can take anywhere from ten years up to a hundred years before they produce their first flower!
Saguaros typically like full sun but tolerate partial shade well.
Soil/potting mix
Saguaro cactus likes well-drained soil that contains compost or other organic matter. Consider using a commercial potting mix, as opposed to regular garden soil, which can be too heavy and compacted for saguaros’ long taproots. Soil should be moist but not waterlogged.
Watering
Saguaros are extremely resilient, but they can’t live without water. They are shallow-rooted plants that survive in arid regions because they have a unique adaptation.
They store water in their trunks until it is needed. This allows them to survive long periods of drought when other plants perish. Proper watering techniques will maximize your saguaro cactus’s health and help it reach its full height potential.
Fertilizer
During saguaro cactus germination, it’s important to ensure that your cacti have good soil nutrition. You can do so by fertilizing them with a liquid fertilizer. The amount you’ll need to use varies based on what size your saguaros are and how many there are, but a general rule of thumb is to use 2 cups of slow-release 20-20-20 for every foot high.
For example, if you have a 12 tall saguaro cactus, then mix 4 tablespoons of the fertilizer in 1 gallon of water.
Temperature
The saguaro cactus is extremely temperature-sensitive. Under favorable conditions, it will grow up to 10 inches a year, but in cooler regions, that number is closer to half an inch.
Though its growth slows dramatically when temperatures dip below 30 degrees Fahrenheit, it will survive these conditions by stopping the growth and going dormant until warmer weather returns.
Humidity
Saguaros like dry conditions and do not like humidity, so keep them away from high-humidity areas. The soil should be well-drained. Plant sahuaros as early in spring as possible so they have time to become established before the summer heat arrives.
Be sure to place sahuaros in areas where they’ll get at least six hours of sunlight a day; otherwise, they may grow more slowly or stop growing altogether during winter.
The ideal humidity range is 40% to 60%. Saguaros are killed in low-humidity environments with less than 10% humidity. They can tolerate brief periods of high-humidity weather without damage, but prolonged exposure will cause leaf loss and stunted growth.
Pruning
For most cacti, it’s important to keep their branches trimmed and in check. Though they don’t need to be cut often, saguaros will do best if you prune them about once a year.
Use pruning shears or scissors. To remove damaged arms, use clean cuts and make them as close to each joint as possible. You can also paint the exposed wounds with latex house paint or a diluted bleach solution to protect against infection.
If the branch has become so large that the stem is now showing through, either trim the branch down with a knife or bend the branch back on itself and allow it to dry out until only its tip remains alive before removing it from the ground.
When to repot
There are some signs that you can look for to know when it’s time to repot your cactus. If a stem is rotting and falling off, it’s time to repot. When new growth appears at its base, that is also a sign that your cactus needs to be repotted. You should definitely move your plant if you notice that it has not grown in two years.
Dormancy/Winter rest
Unlike most cacti, the Saguaro cactus is not able to survive through freezing temperatures. They enter a dormancy stage called winter rest that helps them endure even extreme cold conditions.
During winter rest, when nighttime temperatures dip into the low- to mid-20s Fahrenheit, saguaros lose their green color and slow down their metabolism.
Their skin becomes covered in a white powdery substance made up of waxes, which insulates the plant against the cold. The winter rest is an important time for growth and rejuvenation; it also allows these plants to store up enough water during the hot summer months so they can survive during the drought season of late fall and early spring.
Saguaro cactus flower & fragrance
The saguaro cactus bears large, fragrant white flowers only once every few years. Some grow in clusters and have a fruity smell while others are individually scented.
These spectacular blooms usually occur in April or May when temperatures rise over 70 degrees. The pollinator of choice is a small insect known as a saguaro blossom moth whose sole purpose is to lay its eggs on the saguaro cactus fruit, which looks like an orange-red berry with spines.
Growth rate
Young saguaros grow at a rate of about an inch or two per year, and most of their growth happens in their first 15 years. After that, they grow more slowly, between .5 and 2 inches a year.
Toxicity
Saguaros, which can grow as tall as 40 feet, are known to be non-toxic. However, their branches and spines can cause painful puncture wounds if handled carelessly. When Arizona was part of Mexico, saguaros were used by locals to make tequila. This was done by cutting a cavity into a cactus and fermenting corn into alcohol inside it.
USDA hardiness zones
Saguaro cactus thrives in USDA hardiness zones 9 and 10. They can be grown as a houseplant or outdoors in regions where the temperature does not fall below freezing for extended periods of time.
In regions with cold winters, it is best to keep saguaros outside only during the summer months, bringing them indoors during winter.
Pests and diseases
While most people associate cacti with deserts, some types do grow in woodland or grassland areas. Both wild and cultivated Saguaro cactus are susceptible to a number of pests and diseases. The most common diseases include root rot, leaf spots, rusts, cankers, and crown rot.
Saguaro cactus are sometimes attacked by beetles, snails, and armadillos. Two other notable pests are aphids and psocids – tiny flying insects that look like yellow-gray gnats.
Psocids suck sap from the plant’s tissue and cause necrosis. Aphids damage the plant by inserting their long mouthparts into it, causing it to secrete sugary honeydew, which is then consumed by ants, bees, and wasps.
