Cranberries are one of the few fruits native to North America, sharing this distinction with the blueberry and the Concord grape. Indigenous populations utilized this tart, ruby-red berry for sustenance, medicine, and as a natural dye long before European settlers arrived. The cultivation and harvesting of this fruit relies heavily on a specific natural environment and a complex system of water management.
The Cranberry Plant and Its Necessary Environment
The cranberry plant is a low-growing, woody perennial vine that spreads along the ground through horizontal stems called runners. From these runners, short vertical shoots, known as uprights, emerge to produce the leaves, flowers, and eventually the fruit. The vines form a dense, matted canopy over the soil, and some established commercial beds, often called bogs or marshes, can remain productive for a century or more.
The plant thrives only in highly specialized geological conditions that naturally occur in temperate climate zones. Its preferred environment consists of layers of sand, gravel, and highly acidic peat soil, which is a mix of decaying organic matter. The cranberry vine is adapted to survive where other crops cannot.
An abundant, reliable source of fresh water is necessary for the plant’s survival and for managing the temperature of the beds throughout the year. The plant requires a period of winter dormancy with sufficient “chilling hours” to properly set its fruit buds for the following season. This specialized habitat naturally limits commercial production to a few regions, primarily in Wisconsin, Massachusetts, New Jersey, and the Pacific Northwest.
Cultivating Cranberries: From Vine to Fruit
Commercial cranberry agriculture begins with preparing the bog, which is an impermeable bed lined with the necessary layers of sand and peat. Instead of planting seeds, new beds are established by scattering vine cuttings, which are then pressed into the sand to encourage rooting and growth. Once established, the cranberry plant operates on a 16-month production cycle, with the flower buds for the next harvest forming in the summer of the previous year.
Ongoing management involves seasonal interventions to protect the perennial vines. During winter, growers flood the beds with water, which often freezes, insulating the dormant vines from extreme cold and desiccation. This winter flood is also used to facilitate sanding, where thin layers of sand are spread over the ice, filtering down to the vines after the thaw to stimulate new root growth.
In the spring and fall, the sprinkler system is turned on to create a layer of water over the vines whenever temperatures drop below freezing. This thin coating of water releases latent heat as it turns to ice, protecting the delicate buds and fruit from frost damage. During the summer, managed hives of honeybees or native pollinators are brought in to ensure the flowers are successfully fertilized, which is necessary for the green berries to develop and mature into the familiar red fruit by autumn.
Understanding Wet and Dry Harvesting
The annual harvest, typically running from mid-September to early November, employs two distinct methods based on the intended use of the fruit. Dry harvesting is a gentle process used exclusively for berries destined for the fresh fruit market. Specialized walk-behind machines comb the berries off the vines and deposit them into burlap sacks, keeping the fruit in its original dry state.
The majority of the crop, however, is gathered through wet harvesting, which begins by flooding the beds with up to 18 inches of water the night before collection. Cranberries contain four small air pockets inside, which causes the ripe fruit to float when submerged. Water reels, sometimes nicknamed “eggbeaters,” are driven through the flooded beds to gently dislodge the berries from the vines.
The buoyant fruit rises to the surface, creating the iconic red blanket of berries visible in the bogs. Workers then use large wooden or plastic barriers to corral the floating berries into a corner of the bed. From there, the fruit is transferred by conveyor or pumped into trucks for transport to processing facilities, where they will be used for juices, sauces, and dried products.