Carnegiea gigantea
Carnegiea gigantea
Saguaro
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Description
Carnegiea gigantea, the iconic saguaro cactus, is a slow-growing desert giant beloved for its towering, ribbed columns and dramatic arms. Given bright, direct sun and very gritty soil, it thrives with minimal water and becomes a striking, long-lived focal point for arid landscapes and warm patios.
Common Names
SaguaroGiant saguaroSahuaro
Context
nativeRegion
Sonoran Desert of southern Arizona, southeastern California, and Sonora, Mexico.
usdaZones
9b–11
companionPlants
Palo verde (Parkinsonia spp.), Ironwood (Olneya tesota), Mesquite (Prosopis spp.), Ocotillo (Fouquieria splendens), Prickly pear (Opuntia spp.), Cholla (Cylindropuntia spp.), Brittlebush (Encelia farinosa)
culturalUses
Fruit traditionally harvested by the Tohono O’odham for syrup and ceremonial wine; dried ribs used for construction and tools; emblem of the American Southwest; protected in many jurisdictions—wild collection is illegal.
Care
Care Requirements
LightFull sun; aim for 6–10+ hours of direct light. Acclimate gradually to avoid sunscald.
WateringExtremely drought tolerant. In containers, water deeply, then let soil dry completely; every 3–6 weeks in warm months, little to none in winter.
SoilVery fast-draining, mineral-rich cactus mix with extra pumice/perlite and coarse sand; slightly alkaline to neutral.
FertilizerLight feeding only during warm months with a diluted, low-nitrogen cactus fertilizer 1–2 times per season.
HumidityLow, arid conditions with good airflow; avoid high humidity and stagnant air.
TemperaturePrefers 70–100°F (21–38°C). Brief light frost tolerated when established, but best kept above ~40°F (4°C) in containers.
Growth & Life Cycle
HabitArborescent, columnar cactus with pronounced ribs; develops arms with age.
Mature SizeTypically 30–40 ft (9–12 m), occasionally to 50–60 ft (15–18 m); trunk to 2+ ft (0.6 m) diameter.
Growth RateVery slow; seedlings grow centimeters per year. Arms often form after 50–75 years.
BloomingLate spring to early summer (often May–June); large nocturnal-to-morning white flowers; pollinated by bats, birds, and bees.
DormancyWinter slowdown; minimal water and cooler, bright conditions.
Propagation
MethodsSeed, Grafting (nursery practice for faster growth)
DifficultyModerate—seed germinates readily but growth is very slow; maintain warmth and dryness.
Best SeasonLate spring to summer for sowing seed in warm, bright conditions.
Maintenance & Notes
PruningRarely needed. Remove only dead or diseased tissue with sterile tools; avoid unnecessary cuts.
RepottingInfrequent. Young plants every 3–5 years into a heavy, well-draining pot; mature specimens seldom repotted.
Pests & DiseasesScale, mealybugs, spider mites, and cactus borers; bacterial necrosis and fungal rot from overwatering; sunscald if moved abruptly to full sun.
ToxicityNon-toxic to pets and people, but spines are hazardous; handle with thick gloves and tools.
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