My Young Leaves Are Turning Yellow Between the Veins — Is It Iron Deficiency?

Interveinal chlorosis — a distinctive pattern where leaf tissue yellows while veins stay green — on young, new leaves is the clearest sign of iron deficiency in garden plants. Unlike nitrogen deficiency, which starts on old leaves, iron deficiency hits the youngest tissue first because iron is relatively immobile within the plant and cannot easily be moved from old tissue to new. The cause is almost always not a lack of iron in the soil, but the soil chemistry that prevents roots from absorbing it.

Why Plants Cannot Access Iron Even When It Is Present

Iron is abundant in most garden soils. The problem is solubility. Iron exists in two forms: ferric iron (Fe³⁺), which is largely insoluble and unavailable to plants, and ferrous iron (Fe²⁺), which is soluble and plant-accessible. At pH values above 7.0, ferric iron predominates and the soil solution contains almost no usable iron. This is why iron deficiency chlorosis is so common on alkaline, chalk, and limestone soils, and in soils where over-liming has raised pH too high. Waterlogged soils have the opposite problem — iron becomes too soluble in anaerobic conditions — but iron deficiency is the more common garden scenario.

Plants Most Susceptible to Iron Deficiency

Blueberries, raspberries, camellias, rhododendrons, and azaleas are highly susceptible because they evolved in acidic conditions and have limited ability to acidify the soil around their roots to access iron. Soft fruit grown on neutral to alkaline soil frequently shows chlorosis by midsummer. Among vegetables, strawberries, tomatoes in containers, and occasionally potatoes show iron deficiency symptoms. Fruit trees on alkaline clay, particularly peach, cherry, and plum, commonly show chlorosis on the youngest shoots.

Quick Fixes: Iron Chelate Feeds

Iron chelates are compounds where iron is bound to an organic molecule that keeps it soluble across a wider pH range than simple iron salts. Applied as a soil drench or foliar spray, chelated iron feeds can green up chlorotic plants within one to two weeks. Sequestrene (EDTA chelate) works up to pH 7.5; EDDHA chelate works up to pH 9.0 and is more effective for very alkaline soils. Apply as a soil drench rather than foliar spray for lasting effect — foliar iron feeds green the treated leaves but new growth continues to show deficiency until the root issue is resolved. Iron chelate treatments are a season-long management tool rather than a cure.

Long-Term Solutions

The only lasting solution to iron deficiency on alkaline soil is to correct the pH. For container-grown acid-lovers, switch to ericaceous compost and water with rainwater exclusively. For garden beds, sulphur, acidic mulches, and ericaceous compost work to maintain lower pH over time. On chalk and limestone soils where full pH correction is impractical, accepting that iron deficiency will recur and treating it annually with a chelate drench is a realistic management approach. Improving soil organic matter also helps, as organic acids in humus chelate iron naturally and keep more of it in plant-available form.

Iron Deficiency vs. Magnesium Deficiency

Both produce interveinal chlorosis. The key distinction is which leaves are affected: iron deficiency hits young leaves first; magnesium deficiency starts on older leaves and progresses upward. The vein pattern also differs — in iron deficiency the entire vein network remains green against yellow tissue; in magnesium deficiency the main midrib stays green but the interveinal network also yellows. If you are unsure, test both possibilities by trying an iron chelate drench on one plant and a magnesium sulphate drench on another, and observe which shows improvement first.