Quick answer: Black or nearly black patches on pothos can arise from saturated roots, cold injury, bacterial or fungal leaf disease, or severe physical and light damage. Do not diagnose root rot from leaf color alone. Check for wet potting mix, soft stems, recent cold exposure and whether lesions are spreading.
Start with the pattern and timing
A plant suddenly blackening after contact with a cold window suggests chilling injury. Dark lesions together with a heavy wet pot and rotting stems suggest root stress. Spreading water-soaked patches across several leaves can also warrant investigation for leaf disease. Brown, crisp edges that darken after a dry spell are another pattern. Photograph damage rather than assuming all cases require the same pesticide.
Check drainage and inspect roots when needed
Pothos needs oxygen as well as moisture around the roots. Empty saucers and make sure drainage holes are not blocked. If the plant remains limp in constantly wet mix, gently inspect roots and stem base. Confirmed soft, collapsing tissue can be trimmed using clean tools and the vine repotted into fresh airy mix. Do not strip healthy roots simply because some have brown outer coloration.
Consider cold damage and strong light
Pothos is tropical and does not tolerate freezing conditions. Cold glass, transport without protection or chilly drafts may lead to blackened foliage. Move to a stable indoor location; do not expose injured leaves abruptly to baking midday sun. Intense sunlight can also cause tan or brown scorch that darkens, especially on variegated tissue.
When a leaf disease is plausible
UF/IFAS documents multiple diseases of pothos but notes that cultural disorders can resemble them. If wet-looking lesions keep expanding on different leaves, isolate the plant, avoid leaving foliage wet and seek accurate identification. Fungicide alone cannot cure a root zone that remains flooded; some bacterial conditions are not treated by fungicides.
What to trim and how to monitor
Remove severely dead, collapsing or diagnosed infected tissue with clean shears and keep mostly green leaves when possible. Correct the supported environment problem. Watch fresh foliage for several weeks because old black patches will not become green. Check pest insects if there are sticky deposits, streaked feeding marks or webbing.
Frequently asked questions
Will a black leaf turn green again?
No; severely necrotic tissue cannot recover.
Should I repot immediately?
Only when root condition or failing drainage warrants it.