Carnegiea gigantea, or Saguaro, is one of the largest tree-like cactus grown in the world today. The cactus is native to Southern Arizona and Northern Mexico. Plants in nature will reach up to 60 feet (18 m) tall with the trunks being up to 2 feet (60 cm) in diameter. They will have from 12-30 ribs with 25-30 needle to awl-shaped spines per areole. Spines are yellowish in the new growth to brownish-gray in old growth and are from 0.5 to 3 inches (1.2-7.6 cm) long. They are very slow growers and they make a wonderful container plant for many years before they get too large. Our plant at 21 years old is slightly above 4 feet (~1 m) in height.
Blooming: In the greenhouse, our plant has never bloomed. I have seen these in bloom in the wild. The nocturnal white flowers are up to 5 inches (12.6 cm) long and are followed by red fruit up to 3 inches (7.6 cm) in diameter and are edible.
Culture: Carnegiea gigantea need full sun with a well-drained soil mix. In the greenhouse, we use a soil mix consisting of equal parts loam and sand with small gravel added to ensure good drainage. The cacti are well watered and allowed to dry thoroughly before watering again. We fertilize them once a year with a balanced fertilizer. The plants get the most growth during the winter months in the greenhouse and if the conditions are right they can grow up to 8 inches a year. During this growing period, we keep the plants in a cold room with the nighttime temperatures running at 45°F (7°C) and daytime temperatures running between 65-75°F (18-23°C). During the summer months, the plants are watered enough to keep them from shriveling.
Propagation: Carnegiea gigantea are propagated from seed.
Carnegiea gigantea was featured as Plant of the Week February 10-16, 2006.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.