The iconic images of floating red berries at harvest time often lead to the common question of whether cranberries grow in water. This visual is misleading; the cranberry plant, a low-lying, perennial woody vine, does not grow submerged. It grows on dry land throughout the spring and summer. The association with water comes from a unique and highly efficient, temporary, human-engineered method of gathering the ripe fruit.
The Actual Cranberry Habitat: Bogs and Marshes
Cranberries are cultivated in specialized environments called bogs, a type of wetland often created by glacial deposits. These beds are characterized by a unique soil profile that includes alternating layers of sand, gravel, clay, and peat. The low-lying vines, which can trail up to six feet long, form a dense mat over the bog’s floor.
The growing conditions are specific, demanding a highly acidic, sterile soil and an abundant supply of fresh water for irrigation. Growers manage the water carefully to provide moisture, protect from frost, and enable the harvesting process. They use flooding for winter protection, covering the vines with water that often freezes to insulate the buds from cold and drying winds.
The Purpose of Flooding During Harvest
The dramatic scene of cranberries floating on water is related to “wet harvesting,” a method used for more than 90% of the commercial crop. This process begins after the berries are fully ripened, typically between mid-September and early November. The cranberry beds are deliberately flooded with up to 18 inches of water, turning the dry bog into a temporary pool.
Once flooded, specialized equipment known as water reels, sometimes nicknamed “egg-beaters,” are driven through the field. These machines gently agitate the water, causing the ripe berries to detach from the vine. The water acts as an efficient collection and transport mechanism, replacing the need for hand-picking the fruit from the dense vines.
After the berries are dislodged, the entire crop floats to the surface, creating the signature red ‘sea.’ Workers use large wooden or plastic barriers called booms to corral the floating berries into a corner of the bog. The collected fruit is lifted out of the water using conveyors or pumps and transported for processing into products like juice and sauce.
The Reason Cranberries Float
The entire wet harvesting technique is possible due to a specific biological feature of the cranberry fruit. Unlike many other berries, each cranberry contains four small internal air pockets, or chambers. These air-filled spaces give the fruit natural buoyancy, making it less dense than water.
When the berries are knocked off the vine during flooding, this internal structure causes them to immediately rise and float on the water’s surface. These air pockets also serve a natural purpose, allowing the fruit to float down rivers and streams to facilitate seed dispersal. This physical property of buoyancy explains the image of cranberries floating in water.