Yellow leaves are your plant’s way of saying something is off. The cause is almost always one of five things — and once you know which, the fix is usually simple. Here’s how to diagnose and rescue a yellowing houseplant.
1. Overwatering
The number-one cause. Constantly wet roots can’t breathe and start to rot.
- Lower leaves yellow first, often soft and limp.
- Soil smells sour or musty.
- Fix: Stop watering, let the soil dry, repot if roots smell rotten, trim damaged roots and use fresh mix.
2. Underwatering
- Crispy edges before turning yellow.
- Soil pulls away from the pot.
- Fix: Soak the pot for 20 minutes in a sink of water; let it drain.
3. Light stress
Too little light causes lower leaves to yellow as the plant cannibalizes them. Too much direct sun causes pale, washed-out leaves.
- Move to brighter indirect light if leaves are dropping.
- Move away from a hot window if leaves are scorched.
4. Nutrient deficiency
- Yellow leaves with green veins suggest iron or magnesium deficiency.
- Pale, uniform yellow can be nitrogen.
- Fix: Use a balanced houseplant fertilizer at half strength every 4–6 weeks during growth.
5. Pests and disease
- Look under the leaves and at the soil surface.
- Spider mites, mealybugs, and fungus gnats all cause yellowing.
- Fix: Wipe leaves with diluted soap solution; isolate the plant; sticky traps for gnats.
Practical tips
- Trim yellow leaves — they won’t recover.
- Track changes: photos help you see if a problem is getting better.
- One yellow leaf occasionally is normal. Multiple at once is a signal.
FAQ
Are old plants supposed to drop leaves? Yes, especially after moving or seasonal change. A few yellowing leaves can be normal.
Should I fertilize a struggling plant? No. Fix the underlying issue first; fertilizer stresses sick plants more.
Conclusion
Yellow leaves are diagnostic, not disastrous. Walk through the five causes above and you’ll usually nail the issue in minutes. Pair this with our pillar on indoor plant care for the full troubleshooting toolkit.
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