Snake plant: yellow leaves
Snake plants are close to impossible to underwater and very easy to drown. Yellowing that starts at the soil line, with soft mushy tissue, is rot.
Working through the causes
Start with the first one — on snake plant specifically, that's the most likely explanation. Each entry below names the observable that separates it from the others.
Overwatering / early root rot most common
How to tell: Lowest leaves first, uniformly yellow, soft and limp rather than crisp. Soil is still damp several days after watering, and often smells sour. Sometimes fungus gnats.
What to do: Stop watering and let the pot dry well down. Check that the drainage hole is not blocked and that the pot is not sitting in a saucer of water. If the soil stays wet more than a week, unpot and look at the roots — healthy roots are firm and pale, rotting roots are brown, soft and pull apart easily. Cut those off and repot into fresh, faster-draining mix.
Underwatering common
How to tell: Yellowing arrives WITH crisping — dry, papery edges — and the whole plant looks slightly deflated. Soil has pulled away from the sides of the pot and water runs straight down the gap.
What to do: Soak thoroughly until water runs from the drainage hole, ideally by bottom-watering for 20 minutes so the rootball rehydrates evenly rather than the water tunnelling down the sides.
Natural leaf aging common and harmless
How to tell: One or two of the OLDEST, lowest leaves, while everything above looks healthy and new growth continues.
What to do: Nothing. Plants retire their oldest leaves to fund new ones. Remove it once it is fully yellow.
Too little light common
How to tell: Gradual, widespread pale-yellowing rather than dramatic drop, plus long bare stretches of stem between leaves and any variegation fading toward plain green.
What to do: Move it closer to a window. "Bright indirect" in practice means somewhere you could comfortably read a book all day without a lamp.
Nutrient deficiency less common indoors
How to tell: Yellowing between the veins while the veins themselves stay green, usually on NEWER growth. Typically on a plant that has been in the same soil for years.
What to do: Feed at half strength during the growing season, and repot into fresh mix if it has been more than two or three years. Never fertilize a bone-dry pot — water first.
Cold damage or a draft seasonal
How to tell: Sudden yellowing after a cold snap, often with greasy grey-green patches, and worst on the side facing a window or a door.
What to do: Move it away from the cold glass or the draft. Damaged leaves will not recover; watch the new growth instead.
Plantroster keeps every photo and every diagnosis for a plant, so "sun-scorched" becoming "sun-scorched and mite-infested" three days later is visible instead of lost.
Track this plantQuestions people ask
Should I cut off the affected leaves?
Damaged tissue never turns green again, so removing it is cosmetic — do it if it bothers you, using clean scissors. What matters is whether NEW growth comes in clean. That's your read on whether the fix worked, not the old leaves.
How long until I know it's working?
Give it two to three weeks. Existing damage won't reverse, so you're watching the newest leaves. If those still come in affected after three weeks, the cause you treated wasn't the cause.
More on snake plant
General horticultural guidance based on visible symptoms. A photo or a description can't rule everything out — when a plant matters to you, check the roots before acting.