|A nitrogen deficient tomato leaf|
Nitrogen deficiency occurs if the nitrogen content of the growing medium is not topped up. Heavy rainfall can cause the minerals to be washed away. Compost has the nutrients in it to last for the first months of a plant's life, but plants will become deficient in nutrients if they are not potted on.
Growth dwarfed, thin and upright habit; stem and petioles rigid; leaves pale green, occasional purplish tints, older leaves yellowing.