The timing of when these fruits develop and ripen is highly dependent on both the specific variety planted and the local climate where the tree is grown. Cherries are one of the first tree fruits to ripen in the growing season, marking a transition from spring bloom to summer harvest. The journey from a dormant bud to a ripe, edible fruit follows a predictable annual timeline, but the speed of this process is governed by environmental signals.
The Annual Cycle of Cherry Fruiting
The cherry tree’s annual production cycle begins with the breaking of winter dormancy, typically signaled by rising temperatures in late winter or early spring. This stage, known as bud break, sees the protective scales on the flower buds begin to separate. This is followed quickly by the flowering or bloom period, which usually lasts for about seven to fourteen days in early spring. The bloom is a brief, but highly vulnerable, window during which successful pollination must occur. Once the flowers are pollinated, the tree enters the fruit set phase, where the fertilized ovaries begin their transformation into tiny, immature fruits. The subsequent stage is the period of fruit development, where the small green cherries swell in size over several weeks, leading up to the final ripening phase. Sweet cherries generally require about 60 to 70 days post-bloom to reach full maturity.
Sweet vs. Tart Differences in Ripening Schedules
The ultimate harvest timing is largely determined by the species of cherry, specifically differentiating between sweet and tart varieties. Sweet cherries (Prunus avium) are the type most commonly consumed fresh and typically ripen earlier in the season. Cultivars like ‘Bing’ and ‘Rainier’ are often ready for harvest from late May through late June in the Northern Hemisphere, depending on the region. Tart or sour cherries (Prunus cerasus) are primarily used for cooking and baking due to their higher acid content. The standard tart variety, ‘Montmorency,’ usually becomes ready for picking around mid-summer, extending the cherry season into July.
Key Environmental Requirements for Fruit Set
Successful fruit development depends on the tree satisfying several specific environmental requirements, beginning with a period of cold temperatures during winter. This mandatory cold exposure, measured in “chill hours,” is necessary to properly break the bud dormancy and synchronize flowering. Most sweet cherry varieties require a substantial amount of cold, often between 700 and 1,200 hours at temperatures between 32°F and 45°F (0°C to 7°C). If a cherry tree does not receive sufficient chill hours, its hormonal balance is disrupted, leading to an uneven and delayed bud break.
This results in inconsistent flowering and a fragmented ripening period, which severely reduces the overall yield. Following dormancy, the tree enters bloom, where the critical process of pollination occurs, often requiring bees to transfer pollen between compatible varieties. Most sweet cherry varieties are not self-fertile and require a different cultivar with an overlapping bloom time to achieve a good fruit set. Temperature during bloom is also a major factor; frost events, such as temperatures below 28°F (-2°C), can damage delicate flower buds and reduce the potential crop. Additionally, extreme heat or heavy rain during the final stages of fruit development can cause the cherries to split, impacting viability and harvest timing.
Indicators of Harvest Readiness
Knowing precisely when to pick cherries is vital because they are non-climacteric fruits, meaning they will not ripen further once removed from the tree. The most reliable indicator of maturity is the fruit’s color saturation, which is closely linked to its sugar content and flavor development. For dark-fruited varieties, the color must progress from light red to a deep, mahogany red or black, with the color becoming rich and uniform. A slight loss of firmness is also an indication of ripeness, as the fruit becomes softer and juicier just before the ideal harvest window. Cherries intended for fresh eating should generally be picked with the stem attached, as this helps to maintain freshness and prolongs the shelf life after picking.