How do I treat iron chlorosis?

Test the soil pH. Above about 7 is the usual culprit, and treating the pH is more durable than adding iron. Chelated iron, particularly the EDDHA form, works in alkaline soil where cheaper forms do not.

Will iron chlorosis spread to my other plants?

No. Iron Chlorosis does not spread from plant to plant — each affected plant developed it independently, usually from the same underlying conditions.

Iron Chlorosis

Q: What causes iron chlorosis?

Iron Chlorosis is nutrient problem. Iron chlorosis is usually not a shortage of iron in the soil but an inability to take it up, and the most common reason is soil that is too alkaline. That is why it is so persistent in limestone regions and around new concrete foundations, and why simply adding iron often gives only a brief improvement.

Treatable

Nutrient problem · does not spread · also called interveinal chlorosis

Iron chlorosis is usually not a shortage of iron in the soil but an inability to take it up, and the most common reason is soil that is too alkaline. That is why it is so persistent in limestone regions and around new concrete foundations, and why simply adding iron often gives only a brief improvement.

What it looks like

Leaves yellow between the veins while the veins themselves stay distinctly green, producing a fine green net on a yellow background. Newest leaves are affected first and worst; in severe cases they come out almost white with brown scorched edges.

How to confirm it

Green veins on a yellow leaf — the net pattern is diagnostic.
Newest leaves worst, unlike nitrogen shortage which starts at the bottom.
Common near concrete, paths and foundations where lime raises soil pH.
Overwatered soil produces the same symptom because roots cannot take up iron in waterlogged conditions.

What to do

1Test the soil pH. Above about 7 is the usual culprit, and treating the pH is more durable than adding iron.
2Chelated iron, particularly the EDDHA form, works in alkaline soil where cheaper forms do not.
3Check drainage — waterlogged roots cannot absorb iron regardless of how much is present.
4Elemental sulphur lowers pH slowly over seasons rather than weeks.

What it gets confused with

One observation settles each of these.

Nitrogen deficiency →

Nitrogen yellows the whole leaf evenly starting at the bottom; iron yellows between the veins starting at the top.

Magnesium deficiency

Magnesium also shows interveinal yellowing but on older lower leaves, since magnesium is mobile and iron is not.

Preventing it next time

Match plants to your soil pH rather than fighting it.
Mulch with compost and pine needles for acid-loving plants.

Plants affected

Citrus Hydrangea Roses Maple & Shade Trees Houseplants

Check these two things first

Push a finger into the soil, two knuckles deep. Wet soil plus a wilting plant means too much water, not too little — and it is the commonest reason a plant is dying. Dry soil plus crisp leaves means the opposite. The leaves look nearly identical either way, so the soil is what tells you.
Turn a damaged leaf over. Half of all diagnoses live on the underside: fuzz means downy mildew, fine webbing means spider mites, clusters of insects mean aphids. Nothing on the top of a leaf is as informative.

Most garden problems are cosmetic and resolve without treatment. Reach for a spray last, not first.

Not sure it is iron chlorosis? Run the diagnostic key →