TOMATO LEAVES ARE RED????
Why are the leaves on the tomato plants turning red?
Both phosphorus and magnesium deficiencies turn leaves purpleish or reddish. Magnesium deficiency usually affects the veins and the interveinal areas turn light green or yellow. Phosphorus deficiency generally is more purple because the rest of the leaf stays dark green, but if there is another deficiency (nitrogen) that changes the green to yellow the purple will look redder. Magnesium deficiency affects the oldest leaves first. Phosphorus is more general.