Root Rot in Cymbidiums

This deep dive explains why root rot develops in Cymbidium orchids and why it is one of the most common causes of long-term decline.

The Problem

Cymbidiums affected by root rot may lose vigour, become unstable in the pot, or fail to support normal growth despite regular watering and feeding.

Because symptoms often appear slowly, root loss is frequently advanced before it is noticed.

Root Rot Is Caused by Oxygen Deprivation

Cymbidium roots require both moisture and oxygen to function. Root rot develops when oxygen availability is reduced for extended periods.

When air spaces around the roots collapse, roots are unable to respire and gradually lose function.

Why Water Alone Is Not the Cause

Watering does not cause root rot on its own. Problems arise when water is retained in conditions that prevent air movement.

Fine, compacted, or degraded potting media can remain wet while excluding oxygen, creating conditions that roots cannot tolerate.

The Role of Potting Media Breakdown

As potting media ages, particles break down and pack together more tightly.

This reduces drainage and air space even if watering habits remain unchanged. Root decline often begins slowly as media structure deteriorates.

Cold, Wet Conditions Increase Risk

In cooler conditions, root metabolism slows significantly.

If media remains wet during this period, roots are unable to recover from minor stress and are more likely to collapse.

This is why root rot often progresses during colder months rather than during peak summer growth.

Why Cymbidiums Are Particularly Affected

Cymbidiums are vigorous water users during active growth, which can mask early signs of declining drainage.

When growth slows seasonally, the same conditions that supported growth can become damaging.

Why Root Rot Is Often Misdiagnosed

Above-ground symptoms such as leaf yellowing or reduced flowering are often attributed to nutrition or age.

In many cases, root loss has reduced the plant’s ability to support normal growth long before visible collapse occurs.

Summary

Root rot in Cymbidiums is caused by prolonged oxygen deprivation, most commonly due to compacted or degraded media combined with cool, wet conditions.

Related Care Guide

For broad cultivation guidance, refer to the Cymbidium Orchid Care guide.