Root Rot: Signs and Recovery
Brown slimy roots, sour smell, sudden wilt — save plants from Pythium and anaerobic root zones before they collapse.
What root rot is
Root rot is usually Pythium or similar pathogens thriving in waterlogged, oxygen-starved medium. Healthy roots are white and firm; rotting roots are brown, slimy, and smell sour or musty.
Plants wilt even with wet soil because dead roots can't move water. Top growth yellows, stalls, or collapses fast — days, not weeks.
Symptoms above ground
Match root symptoms to what you see on the plant:
- Sudden wilt with wet medium — classic mismatch
- Yellowing across whole plant, not just lower leaves
- Slow growth or complete stall in veg
- Stem base darkens near soil line
- Hydro: brown roots, slimy texture, reservoir smells off
Recovery steps
Stop watering until soil dries appropriately — or change hydro reservoir completely. Remove dead roots gently if visible at surface; don't aggressively shake roots apart.
Add oxygen: fabric pots, more perlite, air stones in hydro, lower reservoir temp (65–68°F ideal). Beneficial microbes (Bacillus products) help some growers re-establish healthy rhizosphere.
Reduce light stress while roots recover — dim or raise light 20% until new white root tips appear.
Pro tip
Transplant into fresh, airy medium if >50% of root mass is brown — sometimes a reset beats fighting slime.
Prevention
Root rot is almost always environmental:
- Never leave pots sitting in runoff saucers full of water
- Fabric pots + perlite-amended soil improve oxygen
- Coco: frequent feeds with runoff — stagnant wet coco rots
- Hydro: keep res cool, clean, and oxygenated
- Avoid oversized pots for small plants — wet zone persists for weeks
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