Sunlight and heat trigger tomatoes to produce ethylene, the gas responsible for ripening. Once they're ripe, you want to slow the process. Store them in a cool place, about 65 degrees Fahrenheit (18 degrees Celsius), away from heat and light sources, including the windowsill. Use them within three days.
Place partially ripe tomatoes in a closed paper bag to trap the ethylene. They'll come to fruity fullness in three to five days. Include tomatoes in various stages of ripeness to assure a steady supply. Check them daily.
Cold temperatures shut down the tomatoes' ripening mechanism and degrade their tissue. Refrigerate only overripe tomatoes. Better yet, make gazpacho or tomato sorbet. Tomatoes also take well to drying and canning, but freezing leaves them mushy. Thawed tomatoes can replace canned sauce in recipes, though.
Next, we play culinary casting director, finding the tomato "star" for your recipes.