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Yellow leaves · ZZ plant
Why are my ZZ plant leaves turning yellow?
Yellow ZZ plant leaves almost always mean too much water. The plant stores water in its thick rhizomes, so soil that stays damp makes the rhizomes and stems rot, and the leaflets turn yellow. Let the potting mix dry out completely before each watering, never leave the pot standing in water, and if the stems are soft at the base, unpot it and cut out the rotten rhizomes.
Check these first
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Push a finger deep into the potting mix. A ZZ plant should only be watered once the mix has dried out completely; if it is damp, overwatering is the likely cause.
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Squeeze the base of a yellow stem. Firm means the roots are probably fine; soft or mushy means rot.
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Check whether water collects in the saucer or decorative outer pot after watering.
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Note which leaves are yellow: a single old stem fading slowly is normal, many stems yellowing together is not.
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Look at where the plant stands. Leaflets facing a sunny window can bleach and scorch, and a cold window or draft can damage the plant in winter.
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Do not worry about small black spots on otherwise firm, green stems; they are normal on a ZZ plant.
Causes and fixes
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Overwatering and rhizome rot
How to tellLeaflets and whole stems turn yellow, the base of the stems goes soft, and the soil stays damp days after watering. Unpotted, the rhizomes feel mushy and the roots are dark.
What to doStop watering. Unpot the plant, cut off every soft rhizome and stem with a clean knife, let the cuts dry, and replant the firm pieces in a gritty, fast-draining mix in a pot with drainage holes. Water again only once the mix is completely dry.
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Pot standing in water or poor drainage
How to tellThe same yellowing and softening as overwatering, even though you water rarely. The pot has no drainage hole, the mix is dense, or water sits in a cover pot.
What to doMove the plant into a pot with drainage holes and a coarse mix with plenty of perlite or sand, and always let the pot drain fully before putting it back in its cover pot or saucer.
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Too much direct sun
How to tellPale yellow, bleached or brown patches appear only on the leaflets facing a sunny window; the stems are firm and the soil dries normally.
What to doMove the plant out of direct sun to bright, indirect light. Damaged leaflets will not recover, but new growth will be fine.
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Cold
How to tellLeaflets yellow, darken or drop after the plant sat against cold glass, in an unheated room or outdoors as nights cooled.
What to doKeep it somewhere that stays above 15 °C, away from cold windows and drafts, and bring outdoor plants inside before nights drop below that.
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Natural ageing
How to tellNow and then one old stem turns yellow while the rest of the plant stays glossy and new stems keep coming.
What to doNothing is wrong. Cut the yellow stem off at the base once it has faded.
Stop it coming back
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Water only when the potting mix is completely dry: about twice a month in summer and once a month in winter.
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Use a gritty, fast-draining mix and a pot with drainage holes.
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Empty saucers and cover pots after watering so the plant never sits in water.
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Keep it in bright, indirect light, out of hot direct sun.
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Keep it above 15 °C and away from cold glass in winter.
When to worry
When to worry
A single old stem yellowing slowly is part of the plant's normal life. Worry when several stems turn yellow at once or the stem bases go soft: the rhizomes are rotting. Unpot it the same day and cut away every soft part. If only a few firm rhizomes or green stems are left, pot those up on their own in dry, gritty mix; even single healthy leaflets pushed into barely moist mix can root and grow a new rhizome. The black spots that often show on ZZ stems are normal and not a sign of disease.
