Yellow leaves on a Monstera: 6 causes, 6 precise fixes

A yellowing Monstera leaf isn’t a death sentence, and above all, it’s not a diagnosis on its own. The phrase “yellow leaves” covers at least six distinct problems, each with its solution. The good news: the pattern of the yellowing almost always tells you which one.

First, look WHERE the leaf is yellowing

Before asking why, observe the pattern. It’s the key to diagnosis.

• Uniform yellowing of a lower leaf → age or overwatering
• Yellowing between the veins, veins staying green → iron or magnesium deficiency
• Yellow edge then brown, green center → hard tap water or fertilizer too concentrated
• Several yellow leaves at once → watering or roots involved
• Young leaves pale yellow → lack of light or nitrogen deficiency

With this grid, you’ve already eliminated half the hypotheses.

Cause 1. Overwatering (the most frequent)

If several lower leaves are yellowing at once, the base of the trunk is soft, and the substrate stays wet more than a week, it’s almost certain: you’re watering too much.

Excess water drowns the roots, which can no longer breathe. Deprived of oxygen, they rot, and the plant can no longer properly absorb nutrients, even if the soil is full of them. Paradoxical result: your Monstera is starving while soaking.

Fix:

1. Take the plant out of the pot.
2. Examine the roots. Healthy = white/cream, firm. Rotten = brown, soft, smelly.
3. Cut all rotten roots with disinfected shears.
4. Repot in fresh, well-draining substrate (50% compost, 25% pine bark, 25% perlite).
5. Don’t water until the substrate is dry to 3 cm.

Cause 2. Underwatering (the opposite, less frequent but real)

If the yellow leaf is also dry to the touch, almost “papery,” and the substrate is compact and detached from the pot, it’s the opposite: the plant has lacked water too long. The lowest leaves are sacrificed first.

Fix: soaking. Place the pot in a basin of water mid-height for 20 minutes, then drain thoroughly. Resume regular watering (finger check every 5-7 days).

Cause 3. Nutrient deficiency

Yellowing between the veins with veins staying clearly green? That’s the signature of chlorosis, often due to iron, magnesium, or nitrogen deficiency. It happens especially:

• To plants not repotted in over two years (exhausted substrate).
• To plants never fertilized.
• To plants watered exclusively with softened water (a softener removes minerals).

Fix: liquid green-plant fertilizer, diluted by half, every 15 days for a month. If the problem persists, repot in fresh substrate in spring.

Cause 4. Too much or too little light

• Young leaves pale yellow, elongated, without fenestrations → not enough light. Move the plant near an east or west window.
• Discolored leaves with light brown spots in the center → direct sun that burns. Move a meter back or add a sheer curtain.

Cause 5. Tap water

Calcium and chlorine in tap water build up in the substrate over time. Typical symptom: leaf tip and edge browning, the rest turning yellow.

Fix:

• Let water sit 24 h before watering (chlorine evaporates).
• Once a month, water with rainwater or filtered water.
• If possible, flush the substrate under a tap every 6 months to evacuate accumulated salts.

Cause 6. Simple aging

All plants shed their oldest leaves. If just one lower leaf yellows slowly and falls, and everything else is fine, it’s just the natural cycle. The Monstera renews its leaves every 2 to 3 years. Cut the leaf at the base and move on.

When in doubt: the photo settles it

Many symptoms look alike. A yellow leaf with brown edges can be a sunburn, water shortage, or excess limescale. If you hesitate between two causes, photograph the leaf and the plant base: you’ll get an objective diagnosis in under a minute.