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Field guide
Saguaro (Carnegiea gigantea)
Wikimedia Commons

Saguaro

Carnegiea gigantea

Family:
Cactaceae
Elevation:
600 ft – 4,000 ft
Bloom:
May – Jun
Region:
Southwest

The towering, many-armed giant that defines the Sonoran Desert, its pleated green column crowned in late spring with waxy white flowers. A slow-growing keystone that shelters and feeds desert wildlife for well over a century.

Care · tuned to the Southwest

Water

Highly drought adapted; its pleats expand to store monsoon water and contract in drought. Water young plants sparingly and only in the warm season; established plants need little to no supplemental water. Overwatering, especially in cool weather, is the leading cause of rot and collapse.

Sun & exposure

Full sun and reflected heat; young plants naturally establish under nurse trees for shade and frost protection.

Soil

Requires fast-draining, rocky or gravelly, alkaline soil; will not tolerate heavy or persistently wet ground. Plant on slopes or mounds to shed water.

In the Southwest

Strictly Sonoran and frost-sensitive — hard or prolonged freezes damage tissue, so it is not reliably hardy in the colder high desert. Extremely slow growing and long-lived; arms may not appear for many decades. Protected by law in Arizona; do not disturb wild plants. Vital to bats, doves, and native bees.

Common problems & fixes

  • Bacterial necrosis — black, foul-smelling oozing rot in the trunk or arms

    Fix — Cut infected tissue back to firm green flesh with a sterilized blade, let it callus, and remove badly infected plants.

  • Frost damage — blackened, corky tip scarring after a hard freeze

    Fix — Drape frost cloth over the tips of young saguaros during hard freezes below the upper 20s°F.

  • Overwatering and root rot — soft basal collapse from too much irrigation

    Fix — Plant in fast-draining gravelly soil and water established plants rarely, if ever.

Pets & toxicity

No known toxicity to pets; spines are the hazard.

Easy to confuse with

  • Cardon (Pachycereus pringlei) — branches lower and more tree-like
  • Organ pipe cactus (Stenocereus thurberi) — many stems from the base, no central trunk

Sources

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