Leaves on pepper plant turning yellow?

Pepper leaves turning yellow usually point to water stress, weather stress, hungry soil, pests or disease, or spray injury; one or two oldest lower leaves can yellow as the plant matures, but spreading yellowing is not usually just age.

Answer what you can see

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Push a finger two inches into the soil. What does it feel like?

Which leaves are affected?

What has the weather been doing?

How fast did this happen?

These causes can overlap in the answers: dry heat stress and spray burn can both hit the sun-facing side quickly, waterlogged roots and nutrient shortage can both start on lower leaves, and pests or bacterial leaf spot can look like chemical injury until you check leaf undersides and spots closely.

The causes in full

Dry soil and heat stressMOST COMMON

How to tell
Check for soil that is dry 2 inches down, wilting in the hottest part of the day, papery edges, or yellowing that is worst on the side facing the afternoon sun.

What to do
If the soil is dry 2 inches down, water slowly and deeply at the base; if the surface is baked hard, water in two passes so it can sink in instead of running off. Add mulch and use temporary afternoon shade cloth during a heatwave.

Waterlogged roots after heavy rainCOMMON

How to tell
Suspect this when the soil is waterlogged 2 inches down after rain and the plant wilts or yellows even though the ground is wet.

What to do
If the soil is waterlogged 2 inches down, stop watering until the soil is dry 2 inches down. Gently open the crusted surface, pull mulch back until the bed dries, and divert runoff away from the pepper row.

Nitrogen shortage or leached soilCOMMON

How to tell
This usually starts on the oldest, lowest leaves while newer leaves stay greener, especially after weeks of growth or after heavy rain has washed nutrients down through the soil.

What to do
Apply a balanced vegetable fertilizer or a compost side-dressing according to the label, keeping it off the stem and leaves. If the soil is dry 2 inches down, water after feeding; otherwise wait to irrigate until the soil is dry 2 inches down.

Aphids, whiteflies, spider mites, broad mites, or bacterial leaf spotCOMMON

How to tell
Turn leaves over and look for clusters of aphids or whiteflies, fine webbing or pale speckling from spider mites, bronzed distorted tips from broad mites, or dark spots with yellow halos from bacterial leaf spot.

What to do
For insects or mites, dislodge them with a firm hose spray, then use labeled insecticidal soap or horticultural oil on leaf undersides; do not use dish soap. For bacterial leaf spot, work when leaves are dry, clip off the worst spotted leaves, and avoid wetting the foliage.

Cold snap or light frostLESS COMMON

How to tell
Suspect this when yellowing or pale patches show up right after a cold night, especially on exposed leaves or the newest tips.

What to do
If a cold snap caused it, protect the plant on future cold nights with row cover or frost cloth and wait for new growth before judging recovery. Water only when the soil is dry 2 inches down.

Herbicide drift or fertilizer/spray burnLESS COMMON

How to tell
Suspect this when yellowing, bleaching, or odd new growth appears within a day or two after nearby weed killer, lawn spray, strong fertilizer, or another garden spray was used.

What to do
Stop the suspected product, keep future sprays away from peppers, and shield the bed from drift on windy days. Do not fertilize again until you see healthy new growth, and water only when the soil is dry 2 inches down.

Will it recover?

Yellow leaves usually will not turn green again; the goal is to stop the spread and see healthy new green growth.

Stopping it happening again

Prevent repeat yellowing by checking soil 2 inches down and watering deeply only when the soil is dry 2 inches down, mulching the bed, feeding peppers on a vegetable-crop schedule, inspecting leaf undersides weekly, and avoiding sprays on windy or scorching days.