Why Are My Grapevine Leaves Pale Between the Veins?

Grapevine leaves where the tissue between the veins has turned pale yellow, cream, or almost white while the veins themselves remain a darker green are displaying classic interveinal chlorosis. This striking pattern — unlike the uniform overall yellowing of nitrogen deficiency — occurs because the nutrient responsible is immobile in the plant and cannot be redistributed from older leaves. Iron and magnesium are the most common culprits, and the root cause is almost always soil pH rather than an absence of the element in the soil.

Iron deficiency — young leaves affected first

Iron chlorosis appears first on the youngest, most recently expanded leaves at the growing tips of shoots. The interveinal tissue turns bright yellow or even white while the veins stay green, creating a network pattern. This occurs because iron is an immobile nutrient — the plant cannot move it from old leaves to new ones. The vine is almost certainly growing in alkaline soil (pH above 7) or in soil that has been overlimed. Iron is present in most soils but becomes chemically unavailable at high pH.

Magnesium deficiency — older leaves affected first

Magnesium deficiency also causes interveinal chlorosis, but it typically affects older, lower leaves rather than young tips. Magnesium is mobile in the plant and is withdrawn from older leaves to supply young growth when supply is limited. On grapevines, magnesium deficiency often appears mid-season as the vine's demands increase during berry fill. The yellowing starts between the main veins and may spread to cover most of the leaf. Grapevines in sandy or heavily leached soils are most prone.

Diagnosing which nutrient is deficient

Test the soil pH first — if it is above 7.0, iron and manganese lock-up is the likely cause regardless of what is in the soil. If pH is neutral and the older leaves are most affected, magnesium is more likely. A soil or leaf tissue analysis from a laboratory gives a definitive answer. For a quick practical test, apply a small amount of Epsom salt (magnesium sulphate) as a foliar spray to a few affected leaves — improvement within two weeks suggests magnesium deficiency.

Short-term treatment with chelated iron or Epsom salt

Apply chelated iron (sequestered iron) as a soil drench or foliar spray to immediately improve iron availability. Chelated iron remains available at higher pH levels that would lock out standard iron salts. For magnesium, apply Epsom salt as a foliar spray at 20 g per litre every two to three weeks through the growing season, or apply magnesium sulphate granules to the soil in spring. Both treatments provide fast visible improvement within a few weeks.

Long-term soil pH correction

The lasting solution is to bring the soil pH into the optimum range for grapevines (6.0–7.0). Incorporate sulphur chips or acidifying fertilisers annually over several years to gradually lower pH. This is a slow process on chalky soils but the only genuine long-term fix. Testing soil pH before planting and choosing a suitable site avoids the problem entirely for new vines.