Carnegiea gigantea (Engelm.) Britton & Rose
Saguaro, Saguaro Cactus, Sahuaro, Giant Cactus, Sage of the Desert
Cereus giganteus, Pilocereus engelmannii, Pilocereus giganteus
Carnegiea gigantea is a tree-like cactus with a ribbed stem that grows up to 65 feet (20 m) tall and up to 2.5 feet (75 cm) in diameter. It is the largest columnar cactus native to the United States but is extremely slow-growing, reaching only 0.25 inches (0.6 cm) in height after two years. It flowers once it has reached about 30 to 35 years of age and has a height of about 6.6 feet (2 m). The first branches appear after it has reached a height of about 16.5 feet (5 m) and an age of 50 to 70 years. Flowers are white and appear just below the top of the stem. They are up to 5 inches (12.5 cm) long and 2.4 inches (6 cm) in diameter. The fleshy edible fruits are red and up to 3 inches (7.5 cm) long.
The Saguaro blossom is the State Wildflower of Arizona.
USDA hardiness zone 8a to 11b: from 10 °F (−12.2 °C) to 50 °F (+10 °C).
How to Grow and Care
It is not legal to procure a Saguaro Cactus for home cultivation by digging it out of the desert. Beyond that, mature Saguaros almost always die when transplanted.
Saguaro Cactus babies grow under the protection of nurse trees. The cactus will continue to grow, and its nurse tree will often expire. It is thought the cactus may cause the nurse tree to die by competing for resources. The nurse trees shelter Saguaro Cactus babies from the sun's harsh rays and disperse moisture from evaporation.
Saguaro Cactus needs to grow in well-drained grit and receive low water levels, with the soil drying completely between watering. Annually fertilizing with cactus food in spring will help the plant complete its growth cycle.
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