Cherry trees, belonging to the Prunus genus, are valued for their beautiful spring blossoms and summer fruit. The two primary types cultivated for consumption are the sweet cherry (Prunus avium) and the sour or tart cherry (Prunus cerasus). Understanding when these trees fruit involves two distinct timelines: the initial maturation period until a newly planted tree produces its first crop, and the annual seasonal cycle of flowering and harvest.
The Maturation Timeline for First Fruit
A newly planted cherry tree must first reach physiological maturity before producing fruit. The time until the first harvest depends highly on the tree type and the rootstock used for grafting.
Sour cherry varieties tend to begin bearing fruit earlier, typically reaching maturity around three to five years after planting. Sweet cherry trees have a longer juvenile period, often requiring four to seven years before they produce a substantial crop.
The rootstock, the base of the grafted tree, significantly influences this timeline. Trees grafted onto dwarfing rootstocks, such as those in the Gisela series, generally begin fruiting sooner than those on standard, more vigorous rootstocks. These dwarfing systems manage the tree’s size, channeling energy into earlier fruit production.
Annual Fruiting Cycle and Harvest Timing
Once a cherry tree is mature, its fruiting cycle follows a predictable annual pattern, beginning with the breaking of winter dormancy. The timing of bloom and subsequent harvest differentiates the two main cherry types.
Sweet cherries generally bloom earlier in the spring, making them more vulnerable to late frosts. Their harvest window typically begins in late May and extends through July, with different cultivars ripening sequentially during this period.
Sour cherries bloom slightly later than sweet cherries, which offers protection from early spring cold snaps. The harvest for sour cherries, such as ‘Montmorency,’ usually occurs from late June through August. The fruit must be fully colored, plump, and firm when picked, as cherries do not continue to ripen after removal from the tree.
Essential Environmental Factors for Fruit Production
The annual fruiting cycle is initiated by the tree’s ability to break winter dormancy, a process governed by specific environmental cues. This requires the accumulation of cold temperatures, measured in “chill hours.” A chill hour is defined as one hour during which the dormant tree is exposed to temperatures generally between 32°F and 45°F (0°C and 7.2°C).
Most traditional sweet cherry cultivars require a high number of chill hours, often ranging from 700 to 1,200 hours or more to set flower buds. Sour cherries can also have high requirements, with some varieties needing over 1,200 hours.
If the tree does not receive enough cold during the winter, bud break can be uneven or delayed, leading to a poor or absent crop. A late spring frost after the buds have swollen can damage the flower’s reproductive parts, preventing fruit formation. Consistent moisture is important for fruit growth, but excessive water just before harvest can cause the fruit to split on the tree.
Troubleshooting Delayed or Absent Fruiting
When a mature tree fails to fruit on schedule or produces a sparse yield, the problem often lies with factors other than age or chill hours. Pollination failure is a frequent cause, especially for sweet cherries.
Most sweet cherry varieties are self-incompatible, meaning they require a different, compatible cultivar planted nearby for cross-pollination. Without a suitable pollinator, the tree will blossom profusely but will not set fruit. In contrast, most sour cherry varieties are self-fertile, allowing them to produce a crop from a single tree.
Improper pruning techniques can disrupt the fruiting timeline. Cherry trees produce fruit primarily on short, permanent structures called spurs, and heavy winter pruning can inadvertently remove this fruiting wood. An imbalance in nutrients, such as over-fertilizing with nitrogen, can promote excessive leafy growth at the expense of fruit production.
A heavy crop in one year can deplete the tree’s energy reserves, leading to a phenomenon known as biennial bearing. The tree may take the following year to rest and rebuild resources, resulting in a reduced or absent harvest. Pests or diseases, such as brown rot affecting blossoms, can destroy the potential crop.