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A standard sweet cherry tree produces 30 to 50 quarts of fruit a year, while a dwarf tree yields 10 to 15 quarts, according to the National Gardening Association. The trick is to know when to harvest sweet cherry. If you harvest sweet cherry too early, you get a smaller fruit of poor color and taste. If you harvest too late, you get soft fruit that is prone to decay, stem browning and pitting.
The timing of harvest depends on your location and the cultivar, or type of sweet cherry you are growing. If you are in doubt, evaluate your fruit like the pros do and look at the color, taste, firmness and size.
Look for a well-colored sweet cherry crop to appear in July. To meet U.S. minimum maturity standards, 95 percent of the cherry must represent the typical color for the variety, according to The University of California Postharvest Technology Research and Information Center. For instance, a typical Bing cherry is light mahogany, or brownish red. A Royal Ann is yellow with a pink blush.
Determine when to harvest sweet cherry by the sugar content. Commercial growers test soluble solids, or sugar levels, with an instrument called a refractometer. However, most gardeners just rely on taste. So try a couple and if they are not to your liking, then give the fruit 2 to 3 days. The sugar content increases toward the end of the ripening phase.
Check the firmness of the fruit as another indicator of harvest time. Commercial growers use measuring devices, but most home gardeners compress the fruit between their fingers to judge the firmness. It's best to know the typical firmness level of your sweet cherry because each cultivar is different. For example, the Sandra Rose Cherry is only marginally firm when ripe, but the Regina cultivar is very firm.
Measure the size of the fruit. Like the firmess level, cultivars are marked by a standard of size. For instance, the Chelan cultivar yields smaller fruit that ranges from 25 to 28 millimeters in diameter. The Lapins Cherry produces slightly larger fruit that is 28 to 29 millimeters in diameter. Take note that some cultivars, like the Van, overproduce with smaller cherries, then bear fruits biennially.
Harvest sweet cherry in the morning when the weather is cooler. Fresh fruit respires heavily after it is picked. During respiration, plant cells consume oxygen and give off carbon dioxide and energy. The liberated energy is called field heat and it causes shrinkage and sugar depletion in fruit. The rate of respiration is regulated by temperature. If you pick sweet cherry during the day when the weather is warmer, you must remove the field heat quickly with pressure cooling to ensure quality.