Why are my plant's leaves turning yellow?

Updated June 2026 · 6 min read

Yellow leaves (a condition called chlorosis) are your plant's way of waving a flag. The good news: there are really only seven common causes, and most are easy to fix once you know what to look for. Here's how to diagnose yours.

1. Overwatering (the most common culprit)

Soggy soil starves roots of oxygen, and they begin to rot — which shows up as yellowing leaves, often starting low on the plant. The leaves may feel soft, and the soil stays wet for days.

Fix: Let the soil dry out before watering again, make sure the pot has drainage holes, and empty any saucer of standing water. Only water when the top 2–3cm of soil is dry. See our watering guide for the finger test.

2. Underwatering

The opposite extreme also yellows leaves. Here the soil is bone dry, the pot feels light, and leaves may be crispy at the edges as well as yellow.

Fix: Give the plant a thorough soak until water runs from the base. If the compost has shrunk away from the pot, stand it in a basin of water for 20–30 minutes to rehydrate fully.

3. Too little (or too much) light

Plants not getting enough light often yellow and drop their lower leaves as they "give up" on the parts they can't sustain. Too much harsh direct sun, on the other hand, can bleach and scorch leaves pale yellow.

Fix: Move the plant to suit its needs — most houseplants love bright, indirect light. If a plant has been in a dark corner, shift it somewhere brighter gradually over a week.

4. Nutrient deficiency

If the soil is exhausted, plants run short of nutrients — most commonly nitrogen, which causes older leaves to yellow evenly. An iron deficiency, by contrast, yellows new leaves while their veins stay green.

Fix: Feed during the growing season with a balanced liquid fertiliser, and repot tired plants into fresh compost every year or two.

5. Pests

Sap-sucking pests like spider mites, aphids and whitefly drain plants and leave yellow stippling or patches. Check the undersides of leaves for tiny bugs, webbing or sticky residue.

Fix: Wipe leaves down, rinse with water, and treat with insecticidal soap or neem oil. Isolate the plant so pests don't spread.

6. Cold, draughts or shock

Sudden cold, a chilly windowsill, or a draught from a door can yellow leaves. So can the stress of being repotted or moved — plants dislike sudden change.

Fix: Keep plants away from cold glass and draughts, avoid temperatures they're not suited to, and give a newly moved plant a couple of weeks to settle before worrying.

7. It's just natural ageing

Not every yellow leaf is a problem. Plants naturally shed their oldest, lowest leaves as they grow — if it's just one or two at the bottom while the rest looks healthy, that's completely normal.

Fix: Simply remove the spent leaf and carry on.

Quick diagnosis cheat sheet

• Soft, yellow, soggy soil → overwatering
• Crispy, yellow, dry soil → underwatering
• Old lower leaves, even yellowing → nitrogen / natural ageing
• New leaves yellow, veins green → iron deficiency
• Speckled or patchy, bugs underneath → pests
• Pale, bleached patches in bright sun → too much light