Cherries (Prunus spp.) are members of the Rosaceae (or rose) family along with almonds, apricots, peaches, and plums. The two most common types of cherries are sweet cherries (Prunus avium L.) and sour (Prunus cerasus L.), often called tart cherries.
Originally brought to the United States by English colonists in the early 1600s, Spanish missionaries brought cherries west to California. Washington, Oregon, and California are the country’s top growing regions, accounting for 90% of U.S. production. Sour cherries are grown primarily in Michigan, which accounts for nearly three-quarters of annual production.
Types & Varieties
Cherries can generally be classified as sweet or sour/tart. Less common varieties include Duke Cherries, a hybrid of sweet and sour, and Blushed Yellow Cherries, considered a niche category that can be rather difficult to grow and generally more expensive. About 75% of sweet cherries are grown for the fresh market with the rest sent for processing. Conversely, 99% of sour cherries are processed.
The most common sour cherry variety is Montmorency. Popular sweet cherry varieties include Benton, Bing, Brooks, Chelan, Coral, Lambert, Lapin, Rainier, Regina, Royal Ann, Skeena, Sweetheart, Tieton, and Tulare. Low-chill California varieties begin the harvest season in mid-April and generally continue until June when the Washington harvests commence. Oregon follows and U.S. Pacific Northwest harvests end in August, while Canada extends into September.
Fresh market standards for cherries are strict as the fruit is fragile and easily damaged. Fruit not meeting standards is sent for processing, where cherries are frozen, canned, juiced, brined, dried, or made into wine. Sweet cherries are often processed into Maraschino cherries and sour cherries are more often frozen.
Ideal soil for cherry trees is deep, silt loam with low alkalinity and salinity. Cherries can, however, thrive on many types of soil provided it is well-drained and doesn’t remain heavy with moisture for long periods.
Growers commonly plant sod between trees and plant in solid blocks on a raised ridge to encourage drainage and facilitate self-pollinators. Good air flow around the trees is important to discourage frost pockets.
Sour cherries are self-fertile, while sweet cherries are self-incompatible and need another cultivar for pollination. Sweet cherry orchards need one alternate cultivar for every 8 or 9 trees.
Planting at least 2 or 3 cultivars in an orchard is best. For some sweet cultivars, members of the same group will not pollinate each other, so growers must select compatible varieties within a grouping. For both types of cherry, 1 or 2 two honeybee hives per acre is optimal.
Sweet cherries bloom before sour cherries, but both flower in early spring and are susceptible to frost damage. Cherry trees require a dormancy season with extended temperatures between 35 and 55°F to bloom during spring.
Cherries grow for about 60 days after flowering and mature just over 3 months after pollination. Spurs at least 2 years old produce flowers and fruit. Early picking is not an option as cherries can only ripen on the tree, not after harvest.
As trees mature, they are typically trained to either encourage growth along a few selected shoots (open-center training) or structured along a trellis (espalier training).
Orchards are pruned each year to limit tree size and control growth; allow sunlight to penetrate the canopy; promote air circulation; strengthen trees; balance fruiting, flower growth, and vegetative growth; and prevent disease and insect spread. Pruning is generally done by hand.
Sweet cherries are usually picked by color and size as the fruit gets larger and firmer as it ripens. Signs of maturity in both sweet and sour cherries include overall color from light to deep red and 14 to 16% soluble solids content.
Heavy rains before harvest can cause significant losses due to cracking. Cracking is more common in sweet cherries than tart. Sweet cherry picking is labor-intensive, usually requiring upwards of 25 or more workers per acre to complete picking in one day. Sour cherries destined for processing can be mechanically harvested as they part more easily from trees as they ripen.
Cherries are fragile and easily damaged; it is best to pick and cool the fruit as soon as possible after harvest, ideally within two hours. Humidity control is also important to prevent rapid moisture loss (100% humidity is ideal).