Jennifer Schultz Nelson
Extension Educator, Horticulture
The lowly cranberry doesn't get much attention through the year except at holiday time. During the holiday season, fresh cranberries are once again available in the grocery store. How in the world do they get there? Do they grow on a tree, a plant, or what? The answer may surprise you.
Cranberries are native to North America, making them a true "American" fruit. Back in the 1600's, English colonists found cranberries growing wild in what is now Southern Canada and the Northeastern U.S. Native Americans used them along with other berries as a food source. However, there is no solid evidence that cranberries were present at the first Thanksgiving. They certainly could have been, but the written accounts that exist do not specifically mention them.
I remember being taught as a young child in school that cranberries grew in bogs. So for a very long time, I had this picture in my mind of cranberries bobbing along in some sort of swampy bog, growing on huge bushes. In reality, nothing could be further from the truth.
It burst my childhood bubble to find out that cranberries are creeping evergreen shrubs whose stems may stand as high as eight inches above the ground on a good day.
The upright stems arise from an underground rhizome, which is technically modified stem tissue itself. The leaves are exceedingly tiny, at only ¼" to ½" long. The leaves live for two seasons before they are shed.
Flowers bloom on cranberry plants in late June and early July. Whitish-pink flowers occur singly at the end of the upright stems. The flowers hang downward, giving them an upside-down appearance. European settlers in the New World thought the flowers resembled the head of a crane, and so the common name craneberry, or later cranberry was born.
The flowers self-pollinate, and the berries that develop start out green, then turn white and are deep red when fully ripe. This process can take anywhere from 60 to 120 days after pollination depending on the weather and the cultivar.
You may have noticed a somewhat new product in the juice aisle of your local supermarket called white cranberry juice. Sounds pretty exclusive and special, doesn't it? In reality the juice does come from white cranberries, but they are not some special cultivar. Rather, they are fully mature but unripe cranberries. Before someone had the idea to market them as "special" juice, they would have reduced the quality of a batch of cranberries brought in for processing. Now there's a market for them.
Cranberries prefer acidic, sandy soil with added organic matter. Often peat moss is used as the source of organic matter. The idea of a "cranberry bog" comes from the methods used to harvest the fruit and provide winter protection for the plants.
For every acre of cranberries grown, there are anywhere from three to ten acres of "support" land used to store or transport water for the cranberries. The plants are very flood tolerant, but very sensitive to drying out in cold winter winds. The fields are flooded for the winter to protect the plants. This is especially important since next year's flower buds develop at the end of the current growing season. If portions of plants die over the winter, this will potentially decrease the next year's crop yield.
Fall is prime time for harvesting cranberries. Cranberries can be harvested dry, using a series of rakes to "comb" the berries off the plants. The more common method is a "wet" harvest, where individual fields are flooded, and the ripe berries float to the top and are herded to one side and loaded onto a conveyor into a truck.
After being unloaded, the berries are sorted at the processing plant first by bouncing, and later by hand. It sounds silly, but a good quality cranberry will bounce, a bad one will just make a dull thud.
Only a very small percentage of cranberries make it to market as a fresh berry during the holiday season. Another small percentage is sweetened, dried, and marketed as a raisin-like dried fruit. About 90-95% of cranberries end up in a juice or sauce product.
Cranberries are somewhat unique in the world of fruit in that they can be refrigerated without losing quality for several months, and even longer while frozen. So processing the berries into juice, sauce, and dried products can be spread out over the year.
I always thought of the East coast of the U.S. as the major cranberry producer. It surprised me that Wisconsin produces about half of the national cranberry crop, and Massacheusetts is runner-up with about one third of the crop. The rest is grown by Oregon, Washington, and New Jersey.
In theory at least, you should be able to grow cranberries in Illinois if given the right conditions. I have seen cranberries marketed in catalogs and at local garden centers as groundcover in recent years. Their evergreen color and creeping growth habit would make a very attractive groundcover in many situations. However, most homeowners in Illinois would have to do some pretty serious soil amendments to get the acidic, sandy conditions that cranberries love.
But if that doesn't deter you, there's a good chance that with a little attention and proper fertilizing you could grow some cranberries of your own. The good news is that you don't necessarily have to overwinter your plants underwater—a good layer of mulch or floating row cover will also combat the drying winter winds. Even if you don't manage to put homegrown cranberry sauce on your holiday table, having a few of these plants in your garden would be a fun novelty and conversation starter.