Why Are My Plant Leaves Turning Yellow?
Yellowing is a symptom, not a diagnosis. The pattern tells you the cause. Here is how to read it.
Yellow leaves are the garden's most common cry for help, and also its most ambiguous. The same colour can mean too much water or too little, a hungry plant or a waterlogged one. The key is to read the pattern: which leaves are yellowing, where on the plant, and what the rest of the leaf is doing. That pattern points you to the cause.
Read the pattern first
- Oldest, lowest leaves yellowing first, evenly. Usually a nitrogen shortage. The plant is moving nitrogen from old leaves to new growth. Common in fast, leafy crops and hungry soil.
- Whole plant pale and yellowing, soil constantly wet. Overwatering or poor drainage. Soggy roots cannot take up nutrients and effectively drown.
- New, top leaves yellow with green veins. An iron or manganese issue, often because the soil is too wet, too alkaline, or compacted rather than truly short of the nutrient.
- Yellowing with brown crispy edges. Usually drying out, heat stress or salt build-up from over-fertilising.
- Yellow stippling or speckling. Check the underside of leaves for pests like spider mite or aphids.
The most common cause: water, not food
Gardeners reach for fertiliser first, but overwatering is the more common cause of general yellowing. Waterlogged soil starves roots of oxygen and they stop working, which looks exactly like a nutrient problem. Before you feed, check the soil. Push a finger in. If it is wet and the leaves are yellowing, the fix is to back off watering and improve drainage, not to add more.
How to fix each cause
If it is hunger (lower leaves, even yellowing)
Feed with a balanced liquid fertiliser or side-dress with compost or a nitrogen source. Leafy crops respond within a week or two. Build soil with compost over time so it holds fertility.
If it is overwatering (whole plant, wet soil)
Let the soil dry out before watering again, and only water when the top few centimetres are dry. Improve drainage by adding compost, raising beds, or moving pot plants off saucers that hold water.
If it is locked-out nutrients (new growth, green veins)
Improve drainage and aeration first, since wet or compacted soil is usually the real cause. A seaweed or trace-element feed can green things up once the roots can work again.
If it is pests or disease
Turn leaves over and check for insects. Treat sap-suckers with a hose blast and the usual controls. If yellowing comes with wilting that does not recover overnight, suspect a root or vascular disease and remove badly affected plants.
When yellow leaves are normal
Not all yellowing is a problem. The lowest leaves of many plants yellow and drop with age, and seedlings often shed their first seed leaves as the true leaves take over. A few yellow leaves low down on an otherwise thriving plant is nothing to worry about.
Catch problems before they cost you a crop
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Open the App →Frequently Asked Questions
Why are the bottom leaves of my plant turning yellow?
Even yellowing of the oldest, lowest leaves usually means a nitrogen shortage, as the plant moves nitrogen up to new growth. If the soil is also constantly wet, overwatering is the more likely cause. A few aged lower leaves yellowing is normal.
Do yellow leaves mean too much or too little water?
Either, so check the soil. Soggy soil with general yellowing means overwatering, the more common cause. Dry soil with yellowing and crispy brown edges means underwatering. Feel the soil a few centimetres down before deciding.
Should I remove yellow leaves?
You can remove leaves that are fully yellow or dying, as they will not recover and tidying them helps airflow. But fix the underlying cause first, otherwise new leaves will simply yellow too. Do not strip a plant bare.
Will yellow leaves turn green again?
Usually not. A leaf that has lost its green rarely fully recovers. The goal is to fix the cause so new growth comes through healthy and green. Improvement shows in the new leaves, not the old ones.
Why are my plant's new leaves yellow with green veins?
Yellowing between green veins on new growth points to an iron or manganese issue, most often because the soil is waterlogged, compacted or too alkaline rather than genuinely short of the nutrient. Improve drainage and aeration first.
See also: Pest and Disease Guide and Compost and Worms