Root Rot on indoor lemon
What's Happening
Indoor lemon trees are highly intolerant of "wet feet." Persistently damp soil leads to root anoxia and invasion by Phytophthora (oomycetes). This causes yellowing, leaf drop, and eventually mushy black roots. Oversized pots and poor drainage are the primary culprits.
How to Fix It
- 1
Allow the top 2-3 inches of soil to dry completely before watering again (the "knuckle test").
- 2
Repot into a container only 1-2 inches larger than the root ball with multiple drainage holes.
- 3
Use a fast-draining mix (e.g., 5-1-1 mix or citrus-specific soil with 30% perlite).
- 4
Trim rotted, slimy roots and treat with 3% hydrogen peroxide or copper-based fungicide soil drench.
How to Prevent It
Ensure pot never sits in a drainage saucer full of water. Maintain temperatures above 60°F for root health. Use breathable terracotta pots for better aeration.