Germination

• Tomato seeds germinate best at temperatures between 75 to 90 degrees Fahrenheit, according to Cornell University's. Use a heating pad made for seed germination or store them on a radiator or the top of the refrigerator. Once seeds have germinated, they thrive at 70 degrees Fahrenheit.
  
  

Transplanting

• Tomatoes originated in the tropics and thrive in warm, moist conditions. Transplant them after night temperatures are predictably above 45 degrees Fahrenheit. Tomatoes transplanted when day time temperatures are below 65 degrees Fahrenheit are more likely to have cat facing (deformed fruits), according to Cornell University. Use row covers, black plastic mulches or cloches to protect young tomato plants from chilly temperatures.
  
  

Flowering

• When temperatures dip below 65 degrees or rise above 85 degrees Fahrenheit, the flowers may drop, resulting in no fruits. The only option for gardeners in this situation is to wait patiently. Once mild weather returns, the tomatoes will produce fruit again. Cherry tomatoes are less prone to blossom drop than larger beefsteak varieties.