Root rot
How to tell
Healthy orchid roots are firm and silvery or green. If they look brown, flat or mushy and the bark mix stays wet, the rotted roots can no longer supply the leaves, so the leaves go limp. Small dark flies around moist potting medium may be fungus gnats. They suggest conditions suitable for breeding, without proving that the surface never dries.
The fix
Inspect the roots and remove soft, rotten roots with clean tools. Replace degraded bark with fresh orchid mix and ensure drainage. Water when the medium is nearly dry, before the roots dry out completely. Keep water out of the crown.
