Carnegiea gigantea
Light: Full sun when established; young plants benefit from filtered afternoon shade in Phoenix. Acclimate nursery-grown plants gradually.
Water: Very low water once established; rainfall often suffices. During prolonged hot drought, water deeply but infrequently, allowing soil to dry completely. Avoid routine winter irrigation and keep water away from the trunk.
Soil: Excellent drainage is essential; sandy, gravelly desert soil preferred. Avoid low spots, compacted clay, and moisture-retentive amendments.
Mature size: Typically 30–50 feet tall and 10–25 feet wide with arms; develops over many decades.
Bloom: Typically May–June in Phoenix; first flowering generally occurs around 35–50 years of age, depending on growing conditions.
Evergreen / deciduous: Evergreen succulent; green stems provide year-round color.
Growth rate: Very slow, especially when young; growth varies with age, rainfall, and site conditions.