If soil fertility is low, apply 2 or 3 pounds of a complete fertilizer for each 100 square feet of Garden area. Excess nitrogen promotes heavy foliate, reduces fruit yield and increases the chance for blossom-end rot. Nitrogen deficiency predisposes plants to early blight and Septoria leaf spot. Apply monthly thereafter. Ensure adequate and even watering Water stress usually is accompanied by blossom end rot and can make plants more susceptible to early blight and Septoria leaf spot infection.
Tomatoes require about one inch of water a week.
The water should be added gradually and allowed to soak into the soil. Do not allow soil to become so hard and dry that plants wilt. Avoid fluctuations of too much and then too little water. A mulch of grass clippings can prevent a certain amount of evaporation and will also reduce weed growth. Apply fungicides as needed Fungicide applications may be necessary to protect fruit and foliage from anthracnose, early blight, and Septoria leaf spot.