Yellow Leaves On Young Tomato Plants

by Larry Dewitt
(Lafayette, IN)

Q. The lower leaves on my young tomato plants are turning yellow. What can this mean?


A. Yellow leaves can mean several things. Check other symptoms to find out what the problem is.

• Stress. Plants may drop leaves when moved into the garden, especially if they haven't been hardened off sufficiently, if conditions are particularly hot or cold, or if watering is inconsistent.
  
• Nutrient deficiency. Your plant may not be getting enough nitrogen, which is important when they're first set in the ground. Nitrogen stimulates foliage growth. Treat with a balanced tomato fertilizer. Yellowing leaves can also indicate a magnesium deficiency. Treat by watering the soil with a solution of 2 tablespoons of Epsom salts (a good source of magnesium) in a gallon of water.
  
• Early blight. Check to see if leaves also have black concentric spots. Early blight, a fungus, can be treated with copper spray, a biofungicide or a fungicide.
  
• Septoria leaf spot. In addition to yellowing leaves, Septoria (another fungus) also presents with round, yellow or water-soaked spots on the undersides of leaves. They quickly emerge on leaf tops and turn to black or brown with tiny black dots in the center. Like early blight, Septoria leaf spot can be treated with copper spray, a biofungicide or a fungicide.
  
  Tomatoes can recover well from yellowing leaves. Treat plants right away and you'll likely have healthy, delicious tomatoes all season long.
  
  
  Good luck and happy gardening!
  Your friends at Tomato Dirt