Opuntia Cactus Indoors: Brown Spots, Lean & Light Needs

A multi-year Opuntia (likely Grusonia reflexispina) showing brown spots, leaning, and winter decline indoors suffers from insufficient light and possible overwatering in cool conditions.

Spot Diagnosis

• Hard, low spots: Natural woody maturation (corking) — harmless
• Soft, spreading spots: Fungal/bacterial infection from low light + excess water
• Treatment: Spray Lysol every 3 days until spots stop spreading

Light is Non-Negotiable

• Place ON windowsill, blinds open dawn to dusk
• 1 foot back = 50% light loss
• Snow reflection helps — keep near glass
• Maple tree without leaves = minimal shading

Water Protocol

Water ONLY when bone dry. Winter: once/month MAX if <4 hrs direct sun. Summer: weekly if hot/sunny. Never on a schedule.

Stability Fix

Stake leaning stems. Rotate pot weekly. Move outdoors when nights >50°F consistently.