Why are my lemon leaves turning yellow?

Yellow lemon leaves have three main causes. Iron chlorosis: young leaves yellow while veins stay green — apply chelated iron foliar spray. Overwatering: all leaves yellow with soggy soil — reduce watering and improve drainage. Nitrogen deficiency: older leaves yellow first, new growth healthy — apply nitrogen-rich fertiliser. In India's alkaline soils (pH above 7.5), iron lockout is the most common cause. Acidify the soil with sulphur powder or pH-down drops.