Why are my pothos leaves yellowing or curling?

Epipremnum aureum, golden pothos, is the plant people hand to friends who say they kill everything, and it deserves that reputation. It is also the plant I am asked about most often after monstera, because "unkillable" gets read as "needs nothing," and a pothos in a dark bathroom being watered every Sunday will absolutely tell you it is unhappy. The useful thing about pothos is that its two main complaints point in opposite directions, so reading which one you have is most of the diagnosis.

The most likely cause of yellowing: roots that stay wet

Pothos leaves go a soft, even yellow, usually starting with the oldest leaves nearest the soil, when the roots have been sitting in saturated soil. Wet soil has no air in it, roots need oxygen, and roots that cannot breathe stop working. The plant then abandons its oldest leaves to protect its newest ones.

This happens more easily in a pothos than people expect, for a specific reason: pothos gets put where nothing else survives. Windowless hallways, high shelves over kitchen cabinets, the corner of a guest bathroom. In dim light the plant transpires very slowly, so a pot that would dry in five days by a window takes three weeks in the hall. Watering it on the same weekly rhythm you use for everything else keeps it permanently soggy. Same watering can, same amount, completely different outcome, because light is what actually sets the drying speed.

The other causes, in order

• Soil that has gone hydrophobic (this is the classic curling cause). A pothos left dry for long enough shrinks its root ball away from the pot walls, and old peat-based mix repels water once it is fully dry. You water; it runs down the gap and straight out the drainage hole in four seconds; the root ball stays dry in the middle. The leaves cup and curl inward and go limp between waterings. The fix is bottom-watering: stand the pot in a basin of water for twenty to thirty minutes and let it drink from below until the surface is damp.
• Too little light. Small solid-green new leaves, long bare stretches of vine, no new growth for months, loss of variegation. Also the hidden accelerator behind the wet-roots problem above.
• Too much direct sun. Less common indoors, real on a Florida lanai or in a west window. Bleached, washed-out patches, crisping edges, and curling away from the light source.
• Rootbound and hungry. Roots circling the inside of the pot or escaping the drainage hole, water rushing through in seconds, growth stalled. Widespread pale yellowing on an otherwise firm plant. Pot up one or two inches, no more.
• Mineral salt buildup from tap water or fertilizer. White crust on the soil surface or pot rim, yellowing plus brown crispy leaf edges. Flush the pot thoroughly with plain water several times.
• Pests. Mealybugs love the leaf axils of a trailing pothos and hide where the vine drapes over the pot rim. Look for white cottony clusters before you decide it is a watering problem.

How to tell them apart

Do these in order and you will almost always land on the answer.

• Finger test, two inches down. Wet and cold days after watering → wet roots. Dust dry and the pot feels feather-light → dry roots.
• Watch the water go in. If it disappears through the pot in a few seconds and the soil surface stays dry, the root ball is hydrophobic or the plant is rootbound, and every watering you have done recently mostly missed.
• Yellow versus limp. Even yellow, soft to the touch, and thin enough that light shows through it when you hold it up to a window: that is a too-wet signal. Green but curled, cupped, and limp, recovering within hours of a proper soak, is a too-dry signal.
• Where on the vine. Oldest leaves near the soil: normal turnover or wet roots. New growth at the tips affected: something more urgent, usually roots that are already damaged.
• Roots, if you are still unsure. Slide the plant out of the pot. Firm and pale is healthy. Brown, mushy, or sliding out of their own skins means you are looking at root rot and the plan changes.

What to do this week

1. Check the soil before every watering instead of watering on a day of the week.
2. Empty the saucer or cachepot each time; never let the pot stand in water.
3. If water runs straight through, bottom-water once to rewet the whole root ball.
4. Move it somewhere brighter if the new leaves are small, plain, or far apart.
5. Trim leaves that are fully yellow, and cut leggy bare vines back to a few inches to force branching.
6. Check the leaf joints and the underside of leaves for mealybugs while you work.

When to call me

Honestly, most pothos problems are ones you can fix yourself in a week, and I would rather tell you that than sell you a visit. Call when the roots are already damaged, when several plants in the house are going the same way at once (which usually means the watering routine, not the plants), or when you want somebody to audit the light room by room so this stops repeating. That last one is what a health diagnosis visit is actually for.

If your monstera is yellowing at the same time, that is a strong hint the cause is the routine rather than either plant.