Plant diagnosis
Why is my geranium turning yellow?
Window-box pelargoniums are sun-and-air plants — yellow lower leaves mean wet soil, leggy growth means a dim corner, and blackened stem bases mean rot has won.
The 4 most likely causes
The cause of geranium yellow leaves usually narrows to one of the items below, ranked by how often we see each in Growli's diagnostic chats. Work down the list — most readers find their answer in the top two.
- Overwatering or poor drainage (Most likely)
In most homes overwatering is more often a drainage problem than a frequency problem. Geranium needs a pot with a drainage hole, a chunky free-draining mix, and a watering rhythm of water deeply, then let the top third of the pot dry. Soggy soil drowns the roots and the first symptom you see above ground is yellowing or wilting foliage. - Wrong light level (Likely)
Geranium is a high-light plant and quickly turns leggy, pale, or stalled in low light. Move it within a metre of a south or east-facing window, or supplement with a grow light. It wants 6+ hours of direct sun for compact growth and flowers. - Nutrient deficiency (nitrogen or iron) (Possible)
If geranium has not been repotted or fed in a year or more, the older leaves can yellow uniformly while the newest growth stays green — a classic sign of nitrogen depletion. Yellow leaves with green veins on new growth point to iron or manganese deficiency. A balanced liquid feed during the growing season usually resolves both. - Underwatering or letting it dry too long (Possible)
Underwatering looks similar to overwatering at first — both produce limp, dull leaves — but the soil tells the truth. If the soil is dust-dry several centimetres down, water deeply. Geranium prefers water deeply, then let the top third of the pot dry.
Why geranium in particular
Despite the name, a zonal geranium is a Pelargonium from South Africa's dry hillsides, built to shrug off drought and to resent wet feet - so evenly yellowing lower leaves most often mean the roots are sitting too wet, not too dry. A hungry plant in poor soil yellows uniformly from the bottom as well. Watch, though, for a wedge-shaped yellow area spreading from a leaf margin: that pattern, followed by wilting, is a warning sign of bacterial blight.
Normal turnover, or real trouble?
Zonal geraniums are named for the horseshoe band ringing each leaf - a natural marking, not a blemish to fret over. Losing the odd lowest leaf to slow yellowing while the plant keeps flowering is turnover, and a flush of lower yellowing often follows moving a plant indoors for winter as it adjusts to lower light. The yellowing that counts arrives in numbers over damp soil, spreading fast rather than fading one tired leaf.
How to diagnose in 60 seconds
Run these quick checks before you change anything — the right fix depends on what you find.
- Geranium wants water water deeply, then let the top third of the pot dry. Push a finger into the mix and hold it against that: still damp well before it is due, alongside the symptom, is the overwatering signature.
- Are the yellowing leaves the oldest ones at the base, or the newest at the tips? Old-leaf yellowing is usually water or nitrogen; new-leaf yellowing is usually iron or root damage.
- Look at the back of a yellow leaf with strong light — any speckling, webbing, or sticky residue? That points to pests, not water.
- Tip geranium out of its pot and look at the roots: firm and pale is healthy; brown, soft or sour-smelling is rot, which is the real cause behind most of these symptoms.
The fix — step by step
Reach for the can less, not more. Because this dry-country plant yellows chiefly when its roots stay wet, first let the top centimetres of compost dry hard, tip water from the saucer, and check the pot drains - a blocked hole undoes everything. Only once it is not waterlogged should you feed: a hungry, well-drained geranium greens up fast with a balanced feed, while a soggy one rots quicker.
This is the recovery sequence Growli walks users through for geranium with yellow leaves. Work through the steps in order; skipping ahead is the most common reason a plant fails to bounce back.
- Stop watering and check the roots. Don't add more water yet. Unpot geranium and look at the rootball — firm white roots mean you have time; brown mushy roots mean you need to act today.
- Trim damaged roots and yellow leaves. Cut off any soft brown roots with clean scissors. Remove fully yellow leaves at the base — they won't green back up. Leave half-yellow leaves alone for now; the plant is still pulling nutrients out of them.
- Repot into fresh dry mix. Repot into fresh, well-draining mix in a pot one size up. For geranium, pick a spot with 6+ hours of direct sun for compact growth and flowers.
- Reset the watering rhythm. Water deeply once, then wait. For geranium, that means water deeply, then let the top third of the pot dry. Use a finger or a moisture meter — never a calendar.
- Resume feeding only after recovery. A stressed plant cannot use fertiliser and the salts will worsen the damage. Wait for at least one round of healthy new growth (4-6 weeks) before resuming a half-strength liquid feed during the growing season.
When this can't be saved
Most cases of geranium yellow leaves are recoverable, but a few red flags point to a plant that has gone past the point of return. If you spot any of these, consider propagating a clean cutting and starting over.
- Every leaf has yellowed simultaneously and the stem feels soft at the base — root rot has likely consumed the plant.
- New leaves emerge yellow and crispy and never green up — the growing tip is damaged.
- The soil smells sour or sulphurous even after a thorough drying period.
Prevention
For geranium, the single biggest preventative is matching its native rhythm: water deeply, then let the top third of the pot dry, 6+ hours of direct sun for compact growth and flowers, and a free-draining pot with a working drainage hole. Group geranium with plants of similar needs so you can water them as a batch rather than guessing per-pot. Set a calendar reminder to feed during the growing season but never feed a sick or freshly-repotted plant — wait for healthy new growth first.
Common questions
Why is my geranium yellow leaves?
Geranium yellow leaves is most often caused by overwatering or poor drainage. Stop watering, check the roots for rot, and reset the rhythm to water deeply, then let the top third of the pot dry.
What is the most common cause of geranium yellow leaves?
The most likely cause is overwatering or poor drainage. In most homes overwatering is more often a drainage problem than a frequency problem. Geranium needs a pot with a drainage hole, a chunky free-draining mix, and a watering rhythm of water deeply, then let the top third of the pot dry. Soggy soil drowns the roots and the first symptom you see above ground is yellowing or wilting foliage.
Why does this happen to geranium in particular?
Despite the name, a zonal geranium is a Pelargonium from South Africa's dry hillsides, built to shrug off drought and to resent wet feet - so evenly yellowing lower leaves most often mean the roots are sitting too wet, not too dry. A hungry plant in poor soil yellows uniformly from the bottom as well. Watch, though, for a wedge-shaped yellow area spreading from a leaf margin: that pattern, followed by wilting, is a warning sign of bacterial blight.
How do I fix a geranium with yellow leaves?
Reach for the can less, not more. Because this dry-country plant yellows chiefly when its roots stay wet, first let the top centimetres of compost dry hard, tip water from the saucer, and check the pot drains - a blocked hole undoes everything. Only once it is not waterlogged should you feed: a hungry, well-drained geranium greens up fast with a balanced feed, while a soggy one rots quicker.
Is geranium yellow leaves normal, or a real problem?
Zonal geraniums are named for the horseshoe band ringing each leaf - a natural marking, not a blemish to fret over. Losing the odd lowest leaf to slow yellowing while the plant keeps flowering is turnover, and a flush of lower yellowing often follows moving a plant indoors for winter as it adjusts to lower light. The yellowing that counts arrives in numbers over damp soil, spreading fast rather than fading one tired leaf.
How do I prevent geranium yellow leaves?
For geranium, the single biggest preventative is matching its native rhythm: water deeply, then let the top third of the pot dry, 6+ hours of direct sun for compact growth and flowers, and a free-draining pot with a working drainage hole. Group geranium with plants of similar needs so you can water them as a batch rather than guessing per-pot. Set a calendar reminder to feed during the growing season but never feed a sick or freshly-repotted plant — wait for healthy new growth first.