Cactus · Sonoran native
Saguaro
Carnegiea gigantea · Cactaceae
Also called: Giant Cactus, Sahuaro
Saguaro (Carnegiea gigantea) is a very low-water cactus native to the Sonoran Desert region well suited to Tucson and the low desert. It thrives in full sun.
Saguaro at a glance
- Water use
- Very Low (established)
- Sun
- Full sun; thrives in intense reflected desert heat. Young plants benefit from light nurse-plant shade.
- Mature size
- 25-40 ft H x 10-15 ft W (arm spread); very old plants can exceed 40 ft.
- Growth rate
- Very slow (roughly 1 in per year when young; arms typically not produced until 50-75+ years old).
- Bloom
- White (creamy white flowers with yellow centers) borne at stem tips, Late spring (May-June); the state flower of Arizona. Fruit ripens in June-July.
- Cold hardiness
- Hardy to about 18-20 F for brief periods (USDA zones 9-11); prolonged hard freeze damages tissue, and seedlings are frost sensitive.
- Soil
- Well-drained, gravelly to rocky alkaline desert soils on slopes and bajadas; intolerant of poorly drained or heavy wet soils.
- Native range
- Endemic to the Sonoran Desert of southern Arizona, southeastern California, and Sonora and Baja California, Mexico; the iconic columnar cactus of the Tucson region.
- Best used as
- Specimen / signature accent, Architectural focal point in xeric landscapes, Wildlife habitat plantings
- Wildlife
- Keystone species: Gila woodpeckers and gilded flickers excavate nest cavities later used by elf owls, purple martins, and others; flowers feed bats, white-winged doves, and bees; fruit feeds birds, mammals, and is harvested by the Tohono O'odham.
- Toxicity
- Non-toxic; fruit is edible. Spines pose a physical hazard.
How to grow Saguaro in Tucson & the low desert
Watering
No supplemental water needed once established in Tucson; relies on natural rainfall. Newly transplanted specimens benefit from occasional deep watering for the first 1-2 summers, then none. Overwatering causes rot.
Fertilizer & nutrients
Essentially none required in native soil. If desired for transplants, a single light application of a low-nitrogen cactus fertilizer in spring; never fertilize in fall/winter dormancy.
Pruning & care
Do not prune; saguaros are not pruned. Damaged or rotting tissue may be carefully removed by a specialist only when necessary.
Notes
Protected by Arizona Native Plant Law - harvesting, moving, or destroying wild saguaros requires permits. Extremely slow-growing and long-lived (150-200 years). Plant nursery-grown or salvaged (permitted) specimens; orient the same face south as in original siting to avoid sunburn.
Sources: Arizona-Sonora Desert Museum (saguaro natural history); Saguaro National Park / NPS; University of Arizona Cooperative Extension; AMWUA Landscape Plants for the Arizona Desert