Cranberries, A Holiday Tradition

Cranberries have long been part of holiday traditions. They have been made into sauces, jellies, and relishes to accompany holiday meals. They have been baked in pies, tarts, muffins, and breads. They have even been used in holiday decorating, strung with popcorn to make a festive garland.

When we think of cranberries, Pennsylvania is probably not a state that first comes to mind. Indeed, Wisconsin is the largest grower of cranberries, followed by Massachusetts, New Jersey, Washington, and Oregon. Other states, such as Delaware, Maine, New York, Michigan, and Rhode Island, also grow cranberries to some extent. While not a commercial producer, there are many areas in Pennsylvania where cranberries grow naturally in the wild.

There are two cranberry species native to Pennsylvania: American or large cranberry (Vaccinium macrocarpon), the common, commercially grown variety, and small or bog cranberry (Vaccinium oxycoccos). Members of the heath family (Ericaceae), cranberries are hardy in USDA Plant Hardiness Zones 2 through 7. These low-growing, vine-like shrubs have evergreen leaves that have a copper color in the spring, mature to dark green in the summer, and turn maroon in the fall. Both species have small, glossy, ovate leaves. However, the leaves of the small cranberry are smaller with rolled edges that are dark green above with a lighter, whitish underside. Blooming from May to July, their pale pinkish-white flowers have four backward-pointing petals that some say have the appearance of shooting stars or crane's beaks. Due to this resemblance, European settlers to North America originally called them "craneberries", which was later shortened to cranberries. The flowers, pollinated by bees, give rise to the tart berries we are familiar with in August through November.

Wild cranberries grow naturally in bogs. Bogs are freshwater wetlands that receive most of their water from rain and snow rather than from runoff, groundwater, or streams. Often, bogs form in kettle ponds or other depressions that are a result of glaciation. The area is typically composed of sphagnum moss, which will easily absorb and retain water. As sphagnum moss dies, it slowly decomposes, forming a layer of peat moss, creating an acidic, nutrient-poor environment. In Pennsylvania, three protected areas provide visitors with a close-up view of these unique ecosystems:

• Spruce Flats Bog and Wildlife Area in the Forbes State Forest
• Black Moshannon Bog Natural Area in Black Moshannon State Park
• Tannersville Cranberry Bog Preserve with walks scheduled by Monroe County Conservation District's Kettle Creek Environmental Education Center

Growing your cranberry plants at home is possible, no bog needed. They can be grown to harvest the fruit, but they also make an attractive ground cover. Before planting, there are a few important considerations. Cranberries do not like to be moved, so site selection is important. Choose a sunny location with fertile, well-drained soil. These plants do not like wet feet. In a natural bog, the soil will stay moist. Though it may occasionally flood, it will not remain wet. Incorporate sand to improve drainage in heavy soils. Adding other soil amendments, such as dehydrated cow manure, compost, or peat moss, can also help loosen the soil. To grow well, cranberries need an acidic soil pH between 4 and 5.5. Before planting, it is important to do a soil fertility test to check the soil's pH and, if necessary, amend accordingly. Repeat soil testing every two to three years to be sure the pH remains in the optimal range.

While cranberries can be grown from unrooted cuttings, starting with rooted cuttings will increase your chance of success. Some nurseries will ship them to you if you can't find them locally. Space your plants 2 to 3 feet apart. They will spread by runners, so you do not want them too close. Be sure not to plant them too deep. The crown of the plants should be right at the soil level, with the roots just under the surface.

Cranberries require average moisture. A good rule of thumb is an inch of rain every ten days. If you have a dry spell, thoroughly soak them to maintain this moisture level.

The center of the berries contains air pockets, making the fruit buoyant in water. Commercial growers capitalize on this during harvest season. For speed and efficiency, the bogs are flooded. Farmers then use machines called water reels to knock the ripe berries off the vines. The floating berries are then easily harvested by large brooms or a vacuum-type pump. As a home gardener, no sophisticated equipment is necessary to harvest your fruit. Just gently remove the berries from the plants when they ripen to a dark red. Be patient, as the plants usually need to be three years old before producing berries.