A soil test is always the best method for determining the fertilization needs of a crop. Information on soil testing is available in the fact sheet Soil Testing , HGIC 1652 . The desired soil pH for tomatoes is between 5.8 and 6.5. Tomatoes are heavy feeders. Use a starter solution for transplants.
Symptoms are a dark-colored dry rot of the blossom ends of the fruit.
Blossom end rot is caused by a lack of calcium in the developing fruit. It may be an indication that calcium is lacking in the soil or that the plant does not have the ability to take up adequate amounts of calcium from the soil. Mulch with 2 to 3 inches of materials such as grass clippings, pine straw and leaves. Mulching prevents rapid soil drying and allows roots to take up available calcium efficiently. Do not overfertilize plants with nitrogen or potash.