Short answer
Root rot in a Rubber Plant (Ficus elastica) is almost always caused by overwatering, which suffocates the roots and leads to fungal decay. The most effective fix is to immediately inspect the root system, prune away any mushy or blackened roots, and repot the plant into a fresh, well-draining potting mix.
Root rot is a serious condition for Ficus elastica, manifesting first as yellowing, drooping, or dropping lower leaves. Because this species prefers to dry out significantly between waterings, persistent moisture in the root zone is a major red flag that requires immediate investigation to save the plant.
Ficus elastica thrives when allowed to dry out between waterings. If water is applied while the soil is still damp, the lack of oxygen in the root zone causes the roots to drown and die, creating a perfect environment for opportunistic pathogens.
Check: Check if the top 2-3 inches of soil have remained damp for more than two weeks, or if the soil smells sour or moldy.
Fix: Remove the plant from its pot to inspect the roots; discard any that are mushy or brown, and replant in a pot with drainage holes using a high-quality, aerated potting mix.
Even with proper watering frequency, heavy or compacted soil can trap moisture around the base of the root ball. Rubber Plants require a potting mix that allows excess water to escape rapidly from the drainage hole.
Check: Observe if water sits on the surface of the soil for more than a minute after watering or if the drainage holes are clogged with debris.
Fix: Amend the soil with perlite or pumice to increase porosity and ensure you are using a pot with adequate drainage holes.
When a Rubber Plant is placed near a drafty window or air conditioning vent, its metabolic rate slows significantly. If watered at the same frequency as in warm months, the roots will fail to uptake the water, leaving the soil soggy and susceptible to rot.
Check: Check for signs of cold damage, such as leaf drop near vents or windows, coinciding with wet, heavy soil.
Fix: Move the plant to a spot with stable temperatures and reduce your watering frequency until the plant resumes active growth.
When to worry
If you observe wilting accompanied by a foul odor from the pot or if more than half of the leaves are dropping, the damage may be systemic and fatal; immediate repotting is required.
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Diagnose my Rubber PlantNo, you should never fertilize a plant suffering from root rot. Fertilizers can cause salt buildup in the soil, which will further stress an already compromised root system.
If the entire root system is rotted, survival is unlikely. You may be able to save the plant by taking healthy stem cuttings and propagating them in fresh water or perlite.
While both can cause leaf drop, overwatering typically manifests with yellowing leaves and a heavy, damp pot. Lack of light usually causes the plant to become leggy with elongated stems and smaller leaf production over time.
Consistent with guidance from: Royal Horticultural Society: Ficus elastica Care Guide, University of Florida IFAS Extension: Ficus elastica Production.