How to Save Bonsai with Root Rot

Root rot is a symptom of damaged roots, often associated with poor aeration or prolonged saturation, but yellow leaves alone do not diagnose it. Confirm the cause before pruning roots or applying treatments.

Originally published 11 April 2014 · Translated, adapted and edited in English by the BlogBonsai Editorial Team

Check the whole picture

Look for persistent wetness, sour odor, soft or dark roots, poor drainage and declining growth. Similar symptoms can come from underwatering, pests, cold damage or light stress. Compare moisture in different parts of the root ball and inspect roots only when justified.

Correct the conditions first

Ensure drainage holes are open and water is not trapped in a cachepot or tray. Review substrate breakdown, pot size, watering frequency and exposure. A compacted medium may need replacement, but timing and the amount of root work depend on species and severity.

Remove only clearly damaged roots

Use clean tools and preserve healthy fine roots. Do not bare-root a weak tree or apply fungicide without identifying the likely pathogen and following local labels. After repotting, stabilize the tree in suitable light and temperature and avoid further styling until recovery is clear.

Know when to seek help

Rapid decline, extensive root loss or a valuable specimen merits assessment by an experienced bonsai practitioner or plant diagnostic service. Root rot recovery is uncertain; a single “rescue recipe” cannot guarantee survival.

Archive note
This page is reconstructed from historical BlogBonsai material. Horticultural details should be interpreted for the species, season, climate and condition of the individual tree.