Arrange to place plants prior to planting by making slits in the plastic at the desired places. Nitrogen Side Dressing Side dressings applied at the right time and at the correct rate can greatly enhance the production of tomatoes. Side dressings are applications of fertilizer along the plants at some stage of growth. They are started when fruit on the first cluster is about the size of a half-dollar and repeated every four weeks through harvest. If they are applied prior to this time, it is very likely that blooms will be blasted and fruit set will be eliminated or reduced.
Ammonium nitrate is the most common nitrogen source.
Apply one tablespoon in a circle around the plant at each side dressing about 12 inches from the plant. Watering For best tomato growth, keep the soil in the root zone moist enough to prevent wilting of tomatoes. If sprinkler irrigation is used, apply as late in the afternoon as possible but early enough to allow foliage to dry before nightfall. Tomato seeds were taken back to Europe where they quickly found favor in the Mediterranean countries of Spain, Portugal and Italy. As the tomato traveled north, it was veiled in mystery.