Yellow Leaves with Green Veins — Iron Chlorosis and How to Fix It

Photo: Dacnoh, CC BY-SA 3.0, via Wikimedia Commons

When the leaf tissue turns yellow but the veins stay distinctly green, that is interveinal chlorosis — the plant cannot make chlorophyll. The useful part is that which leaves go yellow first identifies the cause, because some nutrients move within the plant and others do not.

Read the pattern before you feed anything

• Youngest leaves first, veins sharply green — iron. Iron cannot be relocated, so new growth starves while old leaves stay fine.
• Oldest leaves first, whole leaf pale — nitrogen. It moves freely, so the plant strips old leaves to feed new ones.
• Older leaves, yellow between veins with a broad green V at the base — magnesium.
• Yellow with brown crispy edges, roots dark and soft — not a deficiency at all but root damage from overwatering, which prevents uptake of everything.

The most common cause is not a missing nutrient

Iron chlorosis usually means the iron is present but locked up. Above about pH 7 iron becomes unavailable regardless of how much is in the soil, which is why hard tap water and limestone-rich ground produce it repeatedly. Adding more iron to alkaline soil mostly wastes fertiliser.

Fixing it

1. Check watering first. Soggy compost mimics every deficiency; rule it out before feeding.
2. For iron, use a chelated form (EDDHA for alkaline soils). It stays available where sulphate forms do not.
3. Lower the pH for a lasting fix — rainwater instead of hard tap water, an ericaceous mix for acid lovers, elemental sulphur outdoors.
4. For nitrogen, feed a balanced liquid fertiliser and expect a response within two weeks. If nothing changes, it was not nitrogen.

What will not recover

Leaves that are already yellow rarely regreen fully, especially with iron. Judge the fix on new growth emerging green, and leave the older leaves alone — they are still photosynthesising, badly.

Not sure that's what you have?

Symptoms overlap, and the wrong treatment wastes weeks. Photograph the affected leaf with Sherleaf and you get the diagnosis, a severity rating and a treatment plan in about ten seconds.