PlantRx

Aglaonema yellow leaves

By Karim DiabatePublished Updated How these guides are built

Yellow leaves narrow nothing down on their own, which is why guessing is expensive. What narrows it down on an aglaonema is not the colour but everything around it: which leaves went first, what the mix feels like two inches down, and what the roots look like.

A healthy Aglaonema, photographed for reference
A healthy aglaonema for comparison. This is a reference photo, not a picture of the problem. Photo by Krzysztof Ziarnek, Kenraiz (CC BY-SA 4.0), via Wikimedia Commons.

What is specific to this plant

  • Aglaonema tolerates low light better than almost any other houseplant, so when one declines the cause is much more often cold or wet feet than darkness.
  • It resents cold. Below roughly 15C or 60F the leaves develop greasy dark patches that look like a disease and are not.

What it could be, and how to tell

These look alike in a photograph, so each one below lists what you would ALSO see if that is the cause. Work down the list and stop at the one where the other symptoms match too.

most common

1. Yellowing in a dim corner that is not about the light

What else you would see

  • a plant in low light that has been there a long time without trouble
  • mix that stays wet between waterings
  • a cold as well as dark position
  • the yellowing spread across the plant rather than on the oldest leaves
How to confirm it: Resist the obvious answer and check the mix and the temperature. An aglaonema tolerates low light better than almost any other houseplant, so when one in a dim corner declines, the darkness is the most visible feature of that corner and almost never the cause. Corners that are dark are usually also cold and poorly ventilated, and those are what this plant minds.

What to do

  1. Check the mix, and let it dry two inches down before watering again.
  2. Move it away from cold and draughts rather than chasing brighter light.
  3. Repot if the mix stays wet for more than a week.
common

2. Overwatering, and the root rot that follows

What else you would see

  • leaf bases that slip off the stem wet rather than drying on it first
  • a stem that gives under light pressure just above the soil
  • yellowing running up from the base of the plant rather than appearing all over it
How to confirm it: Slide the plant out of its pot and look at the roots. Healthy ones are firm and pale. Brown, soft, or hollow when you press them means rot, and that changes what you do next completely.

What to do

  1. Stop watering and let it dry down this far: the top two inches.
  2. Check that the pot drains and empty any saucer or decorative outer pot it sits in. Water held out of sight keeps the mix wet whatever you change above it, and it stays invisible until you lift the pot.
  3. If the roots are soft and brown, trim them back to firm tissue with a blade sterilised first and repot into fresh free-draining potting mix.
common

3. Underwatering

What else you would see

  • leaf margins drying inward while the centre of the leaf keeps its markings and stays firm
  • a pot noticeably light, with the mix shrunk from the wall
  • growth stopped with the newest leaf only half open
How to confirm it: Dry soil pulled away from the pot wall, with foliage that improves noticeably within a day of a thorough soak. If a thorough watering changes nothing in twenty four hours, stop assuming thirst and check the roots.

What to do

  1. Water thoroughly until it runs freely from the drainage holes, rather than a splash at the surface.
  2. If the mix has gone water-repellent and the water runs straight through, stand the pot in a basin of water for half an hour to rewet it properly.
  3. Water on dryness rather than on a fixed day of the week, and this is how far it should dry: the top two inches.
less common

4. Not enough light

What else you would see

  • long bare stretches of stem between the leaves
  • each new leaf smaller than the last
  • lower leaves shed while the growing tip carries on
How to confirm it: Stretched growth and shrinking new leaves together, on a plant whose watering is otherwise right. Aglaonema wants medium to low indirect light, which it genuinely tolerates.

What to do

  1. Move it to medium to low indirect light, which it genuinely tolerates.
  2. Cut back the stretched growth. It will not compact again on its own, and cutting back is what triggers branching.
  3. Turn the pot every couple of weeks so it grows evenly.
less common

5. Too much direct sun

What else you would see

  • bleached, pale patches rather than an even colour change
  • damage only on the side or the leaves facing the window
  • leaves warm to the touch in the afternoon
How to confirm it: The pattern settles it: sun damage is one-sided and patchy, while watering problems and ordinary ageing are even across the plant.

What to do

  1. Move it back from the glass or filter the light. Aglaonema wants medium to low indirect light, which it genuinely tolerates.
  2. Bleached tissue does not turn green again. Judge recovery by whether NEW leaves come in a healthy colour.
uncommon

6. Cold or a draught

What else you would see

  • damage that appeared within a few days of a cold snap, or of the heating or air conditioning coming on
  • the plant sits near a window, an exterior door or a vent
  • the damage is worst on the side facing the cold
How to confirm it: Sudden onset on the exposed side only, following a temperature change. A leaf resting against cold glass overnight is enough to do it.

What to do

  1. Move the plant away from the glass, the door or the vent.
  2. Damaged tissue will not recover. Leave it unless it turns soft, which is the point at which it can start to rot.
uncommon

7. Rootbound, or soil that is worn out

What else you would see

  • roots circling the inside of the pot or escaping the drainage holes
  • water running straight through with almost no absorption
  • two or more years in the same pot, and smaller new growth each season
How to confirm it: Lift the plant out and look. A dense mat of circling roots with very little mix left means the pot can no longer hold what the plant needs.

What to do

  1. Repot one size up in spring into fresh free-draining potting mix, teasing the outer roots loose.
  2. Feed during the growing season, following the instructions on the label of whatever you buy.
uncommon

8. Ordinary ageing

What else you would see

  • one or two of the oldest, lowest leaves at a time and no more
  • healthy new growth continuing from the centre or the tip
  • no other symptom anywhere on the plant
How to confirm it: Oldest leaves only, while the plant is still producing new ones. A plant funding new growth from its oldest tissue is working normally.

What to do

  1. Remove the spent leaf at its base with a clean blade, purely for looks.
  2. Nothing else is needed.

Common questions

Will a yellow aglaonema leaf turn green again?

No. Once a leaf has yellowed, that leaf is spent and the plant has already withdrawn what it could from it. Fixing the cause stops the next leaves going the same way; it does not restore the ones already gone.

Should I cut the yellow leaves off my aglaonema?

Once a leaf is more yellow than green, cut it off at the base with a clean blade. While it is only edged with yellow, leave it: the plant is still reclaiming nutrients from it.

How do I tell overwatering from underwatering?

Feel the mix a couple of inches down and feel the stem at the soil line. Wet mix with a soft stem is overwatering. Dry mix pulled away from the pot with firm stems is underwatering. From above the leaves look much the same, which is how a drowning plant ends up being watered again.

Is an aglaonema poisonous to cats, dogs or children?

Aglaonema contains calcium oxalate crystals and is widely listed as harmful to pets and children if chewed. We do not tell you that any plant is safe. If a pet or a child may have chewed any part of one, contact a vet, or Poison Control on 1-800-222-1222 in the US, immediately rather than waiting to see what happens.

Before you act on any of this

This is general plant care guidance for a plant, not advice about people or animals. We never tell you whether a plant is safe to eat or touch, and we never tell you a plant is safe for a child or a pet. If a child or animal may have eaten any part of a plant, contact Poison Control (US 1-800-222-1222) or a vet immediately rather than reading further.

Treatment advice here is deliberately category level. We do not give product names, mixing ratios or application intervals. Whatever the label on the product in your hand says is the instruction that counts, and following it is your responsibility.

Where this comes from

The general horticultural facts behind this differential come from published university extension and Royal Horticultural Society guidance. What is specific to this plant, and the order the causes are ranked in, is ours, and the methodology page says where that reasoning stops being reliable.

Other aglaonema problems

Not sure which one it is?

PlantRx is an iPhone app that reads the photo and gives you the same kind of ranked differential you just read, for your plant specifically, with the evidence it based each answer on. The first diagnosis is free, in full. There is no subscription and no account.

More about PlantRx