Why Did My Coral Cactus Turn Black? Overwatering and Wrong Light

Why Did My Coral Cactus Turn Black? Overwatering and Wrong Light

Coral cactus (a graft of Euphorbia lactea on Euphorbia neriifolia) has minimal roots and cannot tolerate a large pot or frequent watering.

Correct Conditions

• Pot: Small, just larger than the root ball.
• Soil: 50% potting soil, 50% coarse sand.
• Light: Full, direct sun in a south window (blinds open all day) or a fluorescent grow light 12 inches above.
• Water: Only after the soil has been bone‑dry for a week.

Heat Lamp Problem

A heat lamp provides the wrong spectrum and can cook the plant. Use a proper grow light or sunlight.

Verdict

The black, folded-over stem indicates fatal rot. Start a new plant with the correct setup above.