Nitrogen deficiency

Nitrogen-hungry crops show uniform yellowing of the oldest (lower) leaves first and slow, pale growth, as the plant moves nitrogen to new growth.

Older leaves yellow evenly (whole leaf, not between veins), plant is pale and stunted overall.

Feed with a nitrogen-rich organic fertiliser (blood and bone, pelletised manure) or a diluted liquid feed for a quicker response.

Build soil with compost, keep leafy crops fed during growth, and rotate with nitrogen-fixing legumes.