Any plant that turns pale green, then yellow, with weak, thin, pink-coloured stems and spindly growth may be deficient in nitrogen. Leaves may also turn yellow or red along the veins and die off. Nitrogen is easily leached out of the ground, especially in poor, light soils, and its deficiency is one of the most common plant disorders.

Control

Regularly dress the soil with well-rotted manure and balanced fertilisers. Apply a high-nitrogen fertilizer, such as sulphate of ammonia or dried blood to correct any acute deficiencies.