Yellow leaves are the single most common houseplant complaint, and also the least specific. Overwatering, underwatering, root rot, low light, nutrient deficiency, pests, and plain old age can all turn a leaf yellow, and several of them look nearly identical at a glance. The good news: which leaves are affected, and what the soil feels like, narrow it down fast.
Start here: which leaves are yellowing?
This single question does more diagnostic work than almost anything else. Older, lower leaves yellowing first points toward overwatering, root stress, or simple aging, plants often sacrifice their oldest leaves first when resources are tight. New growth yellowing while older leaves stay green points more toward a nutrient issue, pest damage, or a root problem serious enough to affect the whole plant.
Check the soil next
- Soil is wet, and has been for days: overwatering or root rot. See our watering guide and root rot guide.
- Soil is bone-dry several inches down: underwatering. Yellowing from drought usually comes with crispy, not soft, leaf texture, and the plant often perks back up within a day of a thorough watering.
- Soil moisture seems fine either way: move on to light, nutrients, or pests below.
If the soil isn't the answer
Low light
A plant that's not getting enough light for its needs will sometimes yellow and drop older leaves as a way of reducing how much foliage it has to support. This tends to come with slowed or stopped new growth, and leggy, stretched stems reaching toward the nearest light source. See our guide on matching plants to window direction if this seems like the cause.
Nutrient deficiency
Uniform pale yellowing across older leaves, without any crispiness or softness, can point to a nitrogen shortage, especially in a plant that hasn't been fed in a long time or was recently repotted into nutrient-poor soil. Yellowing that shows up as a pattern, dark green veins against a yellow leaf, points more specifically toward an iron or magnesium deficiency. Our fertilizing guide covers how to feed correctly without overdoing it.
Pests
Check the undersides of leaves and the stems before ruling this out. Fine stippling, sticky residue, or small visible insects point to a pest problem rather than a watering or light issue. See our pest identification guide for the specifics.
Ordinary aging
A single older leaf near the base of the plant turning yellow and dropping, on a plant that otherwise looks healthy and is still growing, is often just that leaf reaching the end of its natural life. This is normal on most houseplants and isn't something to fix.
Putting it together
- Check the soil moisture first. Wet and yellowing points to overwatering or root rot; dry and yellowing points to underwatering.
- If soil moisture doesn't explain it, check which leaves are affected. Old leaves suggest aging, nutrient shortage, or mild root stress; new leaves suggest a nutrient or pest problem worth a closer look.
- Flip a few leaves over and inspect stems for pests before ruling anything else out.
- If nothing above fits and new growth has stalled, reconsider light levels.
Most yellow-leaf mysteries resolve once the soil and the pattern of which leaves are affected are actually checked, rather than guessed at from across the room.