Modern cranberry cultivation practices start with the preparation of individual beds, each bed being a rectangular area of land about 2 to 4 acres in size. The top layer of soil is scalped off to provide material to build dikes around the perimeter of the bed. Proper grading of new beds and the dike structures promote the efficient control of water on and off the property.
Contrary to popular belief, cranberries are not grown under water. Cranberries are grown in a sandy, peat soil on dry land. The common misconception comes from the picturesque cranberry harvest scene that has become a standard for artists and photographers capturing the beauty of the little red berry.
New plantings are developed from vine cuttings taken from established beds. The cuttings are spread over the newly prepared bed and knifed into the soil with a planting disk. During the growing season, the vines are irrigated and fertilized. Weed and insect control practices are employed to promote maximum vine growth and fruit production.
It takes a minimum of three years for the new vines to become established enough to begin to produce any fruit. However, full production is not realized for at least five years. The vines will then continue to produce a crop for many decades as long as they are properly nurtured and maintained.
The Growing Season
Typically the cranberry vine begins to show indication of bloom sometime around the end of May. The flowers blossom and appear as a “hook” before the petals open. The flowers start to open around mid-June and by the end of June, all of the flowers are in “full bloom.” During the bloom period, cranberry growers typically bring in approximately 1.5 beehives per acre in order to pollinate the flowers. This amounts to about 9 million bees on an average 100-acre cranberry marsh. These honeybees remain on the marsh throughout the full bloom period, which usually ends in early July. The cranberry vines must be adequately pollinated by bees in order to reach full productivity. That is why this is one of the most crucial times of the growing year. Small berries begin to appear in July and will continue to increase in size and weight during the summer months.
Frost Protection
During the entire growing season, it is critical to protect the plants from frost. For that reason, temperature alarm systems are installed at each property to alert marsh managers of impending frost conditions. Irrigation systems are activated so that a constant stream of water runs over the plants, thus protecting the plant and fruit from freezing.
Harvest
The annual harvest begins in mid- to late September, when the fruit has matured in size and color, and continues for about six weeks. Harvesting is accomplished by flooding the beds with water and using mechanical harvesters. Production is measured in 100-pound barrels.
Process fruit, which is fruit to be used in juice, sauce and other processed food products, is harvested with machines equipped with rotating water reels called beaters. The churning action of the beaters knocks the fruit from the vines, allowing the berries to float to the top of the water. The floating berries are then corralled at one end of the bed and conveyed onto waiting trucks to be taken directly to a receiving station.
At the receiving station, process fruit arrives in 40,000-pound truckloads and is unloaded into water-filled pools. The cranberries are then conveyed inside the receiving station where they are thoroughly cleaned, graded and placed in 1,000-pound wooden bins for frozen storage. Later, the fruit will be pressed for cranberry concentrate.
The Winter Months
Following the harvest, the cranberry vines enter a period of deep dormancy. To protect the plants from dehydration during the harsh winter weather, the beds are flooded with water until a thick layer of ice is formed. The water is then drained, leaving a barrier of ice and air between the cranberry vines and the harsh elements of winter.
The cold winter months play an important role in the following year’s cranberry crop yield. The plant requires a dormancy period during the winter months to be productive the following spring. A typical Wisconsin winter provides the proper conditions for adequate dormancy.
Proper cultivation practices require adding sand to the beds every four years. This is accomplished by spreading a layer of sand on top of the winter ice cover. As the ice melts during the spring thaw, the sand is distributed evenly over the plants’ rooting surface, allowing the vines to begin a new and vigorous growth cycle.