Saguaro Turning Black Inside: Fatal Rot from Cold or Water

Diagnosis

Black interior + root loss = advanced rot. Causes:

• Excess water: Irrigation, poor drainage, low spot.
• Hard freeze: Recent cold snap (<20°F) damages tissue; rot follows.
• Both: Wet soil + freeze = guaranteed rot.

Outcome

The plant is dead. Black tissue will not recover. It will eventually fall – a 3+ ton hazard.

Action Required

• If near structures/people: hire professional removal (crane, rigging).
• Do not attempt DIY – extreme danger.
• Check other saguaros for similar symptoms.

Prevention

• No irrigation after establishment.
• Plant in well-drained mound.
• Orient north/south correctly at planting.

Saguaros survive centuries in nature; cultivation mistakes kill them fast.