Pocket BotanistA monstera (Monstera deliciosa) is a forgiving plant, which is why a yellow leaf on one gets so much attention: it usually means something has been off for a while. The plant drops a leaf reluctantly. The pattern of the yellowing tells you what it is reacting to, and one check of the soil rules most of the causes in or out before you touch anything else.
1. Overwatering, the usual cause
The pattern: several leaves yellowing at once, often the lower and middle ones, sometimes with soft brown or black patches; the soil still wet days after watering; a faint sour smell from the pot; the plant looks droopy despite being damp. Monsteras are climbers from forest floors with fast-draining soil. Sitting in wet mix suffocates the roots, and the leaves yellow because the roots have stopped working.
What to do: stop watering until the top 5 cm (2 inches) of mix is dry. Slide the plant out and look at the roots: white and firm is fine, brown and mushy is rot. Cut rot away with clean scissors, repot into fresh chunky mix (a third bark or perlite), and water sparingly for a month. Then water only when the top of the mix is dry, which for a monstera is roughly every one to two weeks.
2. An old leaf on its way out
The pattern: one leaf, the lowest and oldest, turning evenly yellow over a week or two while every other leaf stays deep green and the plant is pushing new growth. This is normal. A monstera sheds its oldest leaves as it climbs, a couple of times a year. Cut it off at the base once it is fully yellow and forget about it.
3. Too much sun, or too little
The pattern for too much: yellow patches that turn crisp and brown, on the leaves facing the window, appearing after a move or as summer sun strengthens. Monsteras want bright, indirect light; a few hours of direct morning sun is fine, afternoon sun through glass scorches. Move it a meter back from a south or west window.
The pattern for too little: new leaves small, pale yellow-green and without splits, long gaps between them on the stem, and the plant leaning hard toward the window. Move it closer to the light, or add a grow light for the winter. A monstera in a dim corner will survive for years but never look like the photos.
4. Nutrient deficiency
The pattern: older leaves going pale yellow evenly, with the veins staying green longest, on a plant that has not been repotted or fed in a year or more. Potting mix runs out of nitrogen within a few months. Feed with a balanced liquid fertilizer at half strength every two to four weeks through spring and summer, or repot into fresh mix, and the next leaves come in green. Do not feed a plant that is also overwatered; fix the water first.
5. Cold, drafts, or a sudden move
The pattern: yellowing that starts within days of a change, a leaf that was near a cold window in winter, a plant that came home from a shop, or one moved to a new room. Monsteras dislike temperatures below about 13 °C (55 °F) and cold drafts from doors and air conditioning. Move it somewhere steady and warm and it settles; the affected leaves may not recover but the new ones will be fine.
6. Pests
Less common, but spider mites and scale both cause yellow stippling or speckling that spreads slowly. Look at the undersides of the leaves and along the stems: fine webbing and tiny dots mean mites; small brown bumps that scrape off mean scale. Wipe the leaves with a damp cloth, treat with insecticidal soap, and raise the humidity, which mites hate.
Let the app look at the leaf
Open Pocket Botanist and photograph the yellowing leaf. The diagnosis feature returns the most likely cause from the pattern and the smallest correction to try first, and a saved monstera gets a watering reminder tuned to its pot and light. Free on iPhone and Android.
Sources
- Royal Horticultural Society, "Monstera deliciosa (F)." rhs.org.uk
- Royal Botanic Gardens, Kew, "Plants of the World Online: Monstera deliciosa Liebm.." powo.science.kew.org