Harvest tomatoes when the skin is slightly firm, shiny, and uniformly colored for best flavor.
As a tomato ripens it will turn from a vibrant medium-green to a lighter shade, with faint pink or yellow stripes or flushing. Later the skin will mature to a uniform red or pink or yellow or white or green—depending on the variety.
The exact signs of tomato ripeness will vary from variety to variety.
• Harvest a tomato before its skin loses its waxy smoothness.
• Tomato flavor becomes more complex as the fruit ripens. Tomatoes ripen from the inside out.
• The optimal temperature range for tomato ripening is 68°F to 77°F (20°-25°C). Tomato ripening is slowed when temperatures are warmer or cooler than the optimum range. Tomatoes do not ripen at temperatures above 85°F (29°C).
• Green tomatoes that have reached three-fourths of their mature size can ripen off the vine. Place them in a paper bag with an apple or banana at room temperature out of direct sunlight; ethylene gas given off by the fruit will speed tomato ripening.
• If temperatures turn hot for an extended period, tomatoes on the vine will turn a yellowish-orange color and not be flavorful; in very hot regions, it is better to harvest tomatoes at the pink stage and ripen them at cooler temperatures indoors. More tips at How to Grow Tomatoes.
• In the fall when a frost or a freeze threatens, nearly mature green tomatoes can be picked and wrapped individually in newspaper and stored at room temperature in the dark until they ripen.
• Harvest tomatoes by cutting them from the vine with a garden pruner or sharp knife. Ripe tomatoes will often come off the vine with a simple twist. Don’t jerk or tug fruit from the vine.
Store tomatoes at room temperature indoors (65°-70°F) or in a shady place outside. At room temperature tomatoes will keep for 4 to 7 days.
• Don’t store or refrigerate tomatoes at temperatures below 55°F (13°C); this will cause flavor compounds to break down.
• Partially ripened tomatoes should not be refrigerated; refrigeration stops the ripening process.
• Ripe tomatoes that are refrigerated will lose their flavor and become overly soft.
• If tomatoes are refrigerated, put them in the crisper section of the refrigerator in a perforated plastic bag; the bag will keep the fruit from drying. Refrigerated tomatoes will lose color, firmness, and flavor.
• Tomatoes can be frozen, canned, or dried for future use. To freeze tomatoes, just wash them, cut out bad spots, and place them on a baking tray in the freezer. Once frozen, store tomatoes in plastic freezer bags until needed.
Periodically check stored tomatoes to remove ripened fruit beginning to decay.
More tips: Tomato Ripening and Frost Coming