Malcom N. Dana, E. Professor
The large cranberry, Vaccinium macrocarpon Ait. has provided the plant material for the establishment of an agricultural industry worth several hundred million dollars annually in the United States and Canada. The early settlers in Massachusetts and presumably New Jersey and the maritime provinces of Canada found the wild berries in the marshlands where other vegetation did not compete strongly. The trailing, woody, evergreen plants spread over and through the moss carpet, usually Sphagnum sp., and pushed the hairlike roots into the moss and above the water level in the marsh.

The cranberry plant evolved in an environment with a plentiful water supply provided by the wicking action of the moss and surface peat layers. It evolved without roothairs - those minute root adaptations that provide great surface area for absorption for most land plants. It produces only a shallow fibrous root system that explores only small amounts of the surface "soil" available for its use. Thus the cranberry is adapted to, and dependent upon, a moist root medium of shallow depths.

The cranberry plant was native to marshlands with high soil acidity in the range of pH 4.0–5.0. The plant will tolerate pH 3.5 and grows very nicely at pH 6.5 in nutrient solution. When the medium approaches pH 7.0 the plant begins to show iron chlorosis from a faulty iron metabolism rather than from a lack of iron in the tissue. The plant does not demand low pH soils but is able to thrive in these sites where the competing vegetation is limited in number of species and population density by the inhospitable root environment.

The initial development of cranberry culture was to build ditches and dikes in the natural marsh, to gain some control of the water supply to the field. I expect the first flooding was done for soil moisture supplementation in the summer and only incidentally did someone discover that a flood would prevent frost and not kill the cranberries. And then someone discovered that you could submerge the plants over winter (several months) and if all went well the plants would be uninjured by this treatment. And thus was born the industry that controls winter dessication, spring and summer frost, and summer soil moisture and expedites harvesting of its crop through the use of water.

The name of the individual who first discovered that cranberries could tolerate submersion for extended periods of time has not been preserved by history. He or she was surely from Massachusetts and was a daring individual who would risk the crop by drowning. Of course, the alternative was to risk the crop to drying out and/or freezing. It was found that with cool temperatures the plant would tolerate submersion for extended periods (months) but at warm summer temperatures the safe period was a matter of hours and one could not safely submerge the flower at all. The oxygen level in the water is the determining parameter for safety of the submerged crop. The depletion of oxygen by

Dana, Malcom N. and Professor, E. (1989). THE AMERICAN CRANBERRY INDUSTRY. Acta Hortic. 241, 287-294
DOI: 10.17660/ActaHortic.1989.241.49

Acta Horticulturae