Carnegiea gigantea
Light: Full sun once established; young plants benefit from filtered afternoon shade in Phoenix. Preserve the original sun-facing orientation when transplanting to prevent sunburn.
Water: Very low water once established; rainfall often suffices. During prolonged hot, dry periods, water deeply but infrequently and let soil dry completely. Keep irrigation away from the trunk and avoid routine winter watering.
Soil: Excellent drainage is essential; sandy, gravelly desert soil is ideal. Avoid low spots, compacted clay, and heavily amended planting holes.
Mature size: Typically 30–50 feet tall and 10–25 feet wide with arms; exceptional specimens grow taller.
Bloom: Typically May–June in Phoenix; flowering usually begins after several decades, often around 30–50 years.
Evergreen / deciduous: Evergreen succulent with persistent green stems and no conspicuous leaves.
Growth rate: Very slow initially; established plants may grow several inches annually, depending on water, temperature, and site conditions.