# Yellow leaves: the decision tree

By the GO AI Team · August 21, 2026

> **TL;DR:** Yellowing is a symptom with at least six causes needing opposite responses. Three questions narrow it: **which leaves** (lowest, newest, scattered), **how fast** (weeks or overnight), **what pattern** (whole leaf, between veins, edges first). Overwatering leads indoors — but watering a plant that's yellow from root rot makes it worse.

## Which leaves?

| Where | Most likely | Check |
|---|---|---|
| Lowest one or two, slowly | Normal ageing | Nothing — if new growth is healthy, this is fine |
| Lower leaves, several, soft | Overwatering | Finger 3–4cm into the soil. Damp? Stop. |
| Newest leaves | Nutrients or light | Last fed when? Same spot for a year? |
| Scattered, fast | Roots or sudden change | Recent repot, move, draught, radiator? |
| Whole plant, dull and limp | Root rot or severe drought | Lift it out and look at the roots |

## How fast?

**Weeks** → chronic: watering habit, light, nutrients, age. Change one variable and watch.
**Days** → acute: root damage, temperature shock, pests, or something you just changed. Look today.

## What pattern?

- **Uniform yellow, whole leaf** — water or age. Most common indoors.
- **Yellow between green veins** — classic nutrient signature.
- **Edges first, moving in** — drought stress, salt build-up, or scorch.
- **Yellow with pale speckles** — check the underside zoomed in. Speckling plus fine webbing is spider mites.
- **Yellow plus mushy brown base** — check the roots now.

## The root check

Slide the plant out. Healthy roots are firm and pale. Rotting roots are brown or black, soft, often sour-smelling. Two minutes, and it converts a guess into an answer. If they're rotting, watering is the opposite of help — trim, repot into fresh dry-ish mix, water sparingly until new growth appears.

## What not to do

- **Don't water because a leaf looks sad.** Too much and too little look identical. Check soil first — this is how most houseplants die.
- **Don't fertilise a struggling plant.** Feed is for growing plants.
- **Don't change three things at once.** You'll never learn which mattered.
- **Don't expect yellow leaves to green up.** Success is healthy *new* growth.

## Judging it

Fix the one thing you're most confident about, photograph the plant today, and set a recheck date one to two weeks out. Daily judgement produces false alarms both ways. Recurring across several plants? The cause is your environment, not the plants.

Distinguishing the two watering failures: overwatered or underwatered?

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