White Cottony Growth on Orchid Media: Mold, Mealybugs, or Scale?

Three weeks in, your purple orchid shows blackening roots and white cottony substance on media and roots. You water weekly by soaking. What's wrong?

Likely Causes

• Mold from overwatering—media stays too wet, breaks down, roots rot, fungus gnats move in.
• Mealybugs—white cottony coating; touch with alcohol to reveal insect body.
• Boisduval scale—hard shell, harder to treat.

Immediate Steps

1. Water less often—wait until media is barely moist.
2. Smell media after watering; sour odor = replace mix.
3. If insects: apply systemic orchid-safe insecticide per label.
4. Identify orchid type and location for specific culture advice.