Short answer
Black spots on a Monstera deliciosa are most frequently caused by fungal or bacterial infections triggered by overwatering or poor air circulation. The single most effective fix is to improve soil drainage, prune the affected leaves, and reduce watering frequency to ensure the top two inches of soil dry completely between sessions.
Seeing black spots on your Monstera deliciosa can be alarming, as they often appear as wet, dark, or mushy patches that may be surrounded by a yellow halo. While some minor spotting can be cosmetic, these dark lesions often indicate that the plant's environment is too damp, potentially leading to root rot if not addressed quickly.
Excess moisture trapped in the soil leads to anaerobic conditions that promote fungal pathogens. The roots begin to decay, preventing the plant from properly cycling water, which manifests as darkened, necrotic spots on the foliage.
Check: Gently remove the plant from its pot to inspect the roots; healthy roots should be firm and pale, while rotting roots will be mushy, brown, or slimy.
Fix: Trim away all mushy, decaying roots with sterilized shears, repot in fresh, well-draining aroid soil mix, and ensure the pot has adequate drainage holes.
In high-humidity environments with stagnant air, fungal spores can colonize Monstera leaves. These spots typically start as small black dots that grow over time and often develop a distinct yellow border as the plant tissue dies.
Check: Check if the black spots are concentrated on older leaves and if the underside of the leaf shows signs of fungal growth or velvet-like spores.
Fix: Remove the most infected leaves to reduce spore spread, improve air circulation around the plant, and avoid misting or getting water directly on the foliage during watering.
Bacterial infections often enter through the stomata or small wounds on the leaf surface. These spots are usually darker, look 'water-soaked,' and can spread rapidly if the leaf surface remains wet for extended periods.
When to worry
You should take urgent action if the black spots are spreading rapidly, emitting a foul odor, or if the stem base feels soft, as these are indicators of systemic rot that can kill the plant.
Not sure which cause it is?
Upload a photo of your Monstera and get a diagnosis in seconds.
Diagnose my MonsteraYes, it is best to remove leaves with significant black spots to prevent further spread of potential pathogens. Always use clean, sharp shears and sanitize them with alcohol between cuts to avoid cross-contamination.
Stem rot is much more dangerous than leaf spots. If the main stem or base of the plant has turned black and mushy, you may need to propagate a healthy vine cutting to save the plant, as the root system may be beyond recovery.
Actually, excessive humidity without proper air movement can exacerbate fungal issues. While Monsteras enjoy humidity, prioritize good ventilation and airflow to keep the leaf surfaces dry rather than just increasing moisture levels.
Consistent with guidance from: Royal Horticultural Society (RHS) Gardening Advice, University of Florida IFAS Extension: Monstera deliciosa Care.
Check: Hold the leaf up to the light; if the black spots appear translucent or water-soaked in the center, it is a hallmark sign of a bacterial infection.
Fix: Isolate the plant immediately, use sterile tools to cut off affected foliage, and strictly avoid overhead watering to keep the remaining leaves dry.