Root rot is a common affliction for the otherwise resilient Pothos plant, Epipremnum aureum, often striking when the soil remains too wet for extended periods. This condition is caused by various water mold fungi, such as Pythium, which thrive in low-oxygen, saturated environments. The lack of oxygen suffocates the roots, allowing these pathogens to take hold and causing the roots to decay. Recognizing this disease early provides the best chance of saving the plant.
Identifying Root Rot
The first signs of root rot often appear above the soil, presenting as symptoms that can be mistaken for underwatering. You may notice leaves turning yellow, typically starting with the older leaves, and a general wilting or drooping of the foliage despite the soil being moist. The plant’s growth will become noticeably stunted, as the damaged roots are unable to absorb water and nutrients.
A definitive diagnosis requires unpotting the plant to inspect the root structure directly. Healthy Pothos roots are typically firm, pliable, and white or light tan in color. In contrast, rotting roots appear brown or black, feel soft and mushy, and may easily disintegrate when handled. A strong, foul odor often emanates from the soil and decaying roots, which indicates anaerobic bacterial activity.
Step-by-Step Treatment
The immediate step involves gently removing the Pothos from its pot and washing the roots under running water to remove all traces of contaminated soil. This allows for a clear assessment of the damage and ensures no fungal spores remain.
After cleaning, trim away all affected root tissue using sterilized scissors or shears. Cut back any roots that are brown, black, or mushy until only firm, healthy, white tissue remains. Sterilizing your cutting tools between snips with 3% hydrogen peroxide prevents the spread of pathogens to healthy root sections.
The remaining healthy root structure should be treated to kill residual fungal spores. A solution of 3% hydrogen peroxide diluted with water is commonly used. Mix one part of the 3% hydrogen peroxide solution with two parts of water, then spray or dip the root ball in this mixture. This releases oxygen, which is toxic to the anaerobic pathogens causing the rot, and helps to aerate the remaining roots.
The next step is to prepare a clean environment for the recovering plant. The old pot must be cleaned thoroughly, ideally with a bleach or soap solution, to ensure no pathogens are transferred to the fresh soil. Alternatively, use a new, sterilized pot.
Repot the Pothos using a fresh, well-draining potting mix; never reuse the old, contaminated soil. A suitable mix consists of standard indoor potting soil amended with chunky materials like perlite or orchid bark to improve drainage and aeration. After repotting, wait several days before watering to allow the trimmed roots to callous and prevent the fresh soil from becoming waterlogged.
Adjusting Care to Prevent Recurrence
The primary factor in preventing root rot recurrence is correcting overwatering habits and improving drainage. Allow the top two inches of soil to dry out completely before watering again. You can test the soil moisture by inserting a finger two inches deep or by using a moisture meter.
Ensure the pot has large, unobstructed drainage holes, as standing water creates the low-oxygen environment where rot pathogens thrive. Avoid using decorative cachepots that hold excess runoff water around the base of the main pot.
The composition of the potting medium is also a defense against recurrence. An airy, porous substrate, achieved by mixing standard potting mix with perlite, aged bark, or coco coir, promotes faster water movement and provides air pockets for the roots. This prevents the soil from becoming dense and compacted, which restricts oxygen flow.
Environmental conditions play a supporting role in the plant’s ability to process water efficiently. Pothos requires adequate light, as insufficient light slows the plant’s metabolic rate and water usage, meaning the soil takes longer to dry. Cooler ambient temperatures also slow water evaporation from the soil, increasing the risk of saturation.