Understanding the journey of cherries from blossom to ripe fruit reveals the distinct phases crucial for their quality. Each stage, from initial flowering to the development of sweet, colorful cherries, contributes to the final harvest.
From Blossom to Fruit Set
The cherry’s annual cycle begins as winter dormancy ends and temperatures rise. Buds begin to swell, showing green tips, then progress through “bud burst” (almost entirely green) to “white bud,” when white petals become visible.
Once blossoms fully open, typically in early spring, insects, primarily bees, pollinate the flowers. While some sweet cherry varieties require cross-pollination, sour cherries are often self-pollinating. Successful pollination leads to fruit set, where the fertilized flower’s ovary swells, forming a tiny, green fruit beneath the spent petals.
Green Fruit Development
Following fruit set, cherries undergo rapid green fruit development. The small fruit grows significantly, remaining green and firm. This phase, known as cell proliferation, lasts approximately 10 to 25 days after pollination, establishing the cherry’s ultimate size potential.
The fruit accumulates carbohydrates but has not yet developed sweetness or color. Cherries remain green for over half their development time, appearing hard and tart. This growth phase establishes the fruit’s physical dimensions before ripening begins.
The Ripening Process
The ripening process transforms the cherry from a hard, green fruit to a soft, sweet, and vibrantly colored one. This second rapid growth phase occurs 15 to 25 days before harvest. During this period, fruit cells expand dramatically due to water and sugar accumulation, contributing to the cherry’s plumpness and juiciness.
Color shifts, driven by pigments like anthocyanins. Most sweet cherries transition from green to yellow, then to red, and finally to deep red or dark purple. Rainier varieties ripen to golden yellow with a pink blush. Simultaneously, starch converts to sugar, significantly increasing sweetness. Sunlight and warmth play a large role, as ample sun exposure helps develop sugars.
Harvest Readiness
Determining cherry ripeness involves assessing several indicators for optimal flavor and texture. Color is a primary visual cue: most sweet cherries show deep red or dark purple, while Rainier cherries develop a golden yellow hue with a blush. Pale or uneven coloring indicates underripe fruit.
Texture is equally important: a ripe cherry should feel firm but yield slightly when gently squeezed, indicating juiciness. Avoid overly soft or wrinkled cherries, which may be overripe. Fresh, green stems are a good sign; dry or brown stems suggest older fruit. Tart cherries typically detach easily when ripe, while sweet cherries may require a taste test. Cherries do not ripen further after picking, making timely harvest crucial for quality.
Factors Influencing Cherry Development
Several environmental factors influence cherry development and quality. Optimal temperatures are important: sweet cherries prefer cooler winters for dormancy and mild summers. Temperatures between 59°F and 68°F (15°C to 20°C) are ideal for spring flowering. Cherries tolerate up to 85°F (29°C) during the growing season, but extreme heat may require protective measures like shade cloth or increased irrigation.
Adequate sunlight exposure is also important; cherry trees need at least 6 to 8 hours of direct sun daily for photosynthesis, fueling growth and fruit production. Insufficient sunlight can lead to fewer blossoms, smaller fruit, and reduced sweetness and color. Water availability is another factor; consistent moisture is necessary during fruit development, though established trees may not require frequent watering. Excessive rainfall, especially during ripening, can cause cherries to crack or split. Late frosts during bloom can also damage blossoms and reduce fruit yield.