VACCINIUM macrocarpon Aiton
By Thelma Glover
Most everyone recognizes the red berries that probably showed up beside the turkey on the dinner table last month, but probably few would recognize the plant that produces these tasty little morsels. It may surprise you to know that this same attractive, diminutive, glossy leaved shrub that bears the fruit that has become an American tradition makes a beautiful, evergreen, easy groundcover with all the attributes of a first class garden plant: ornamentally pleasing, hardy, dependable, easy to propagate, low to no maintenance and four seasonal interest. There is one drawback. At the present it is hard to find a source since nurserymen in Georgia only started propagating it for sale in the last year or so. It is, however, offered by some mail order and specialty nurseries and probably by the spring of l998, it will be more readily available to the public.
Most of us in Georgia haven’t encountered this little jewel because the closest its natural range comes to Georgia is in the mountains of Tennessee and North Carolina. Found in the wild in acid sphagnum bogs from Newfoundland to Minnesota and southward to the mountains of Tennessee and North Carolina, this member of the Ericaceae family is a close relative of the blueberry, which is, of course, in the same genus. Vaccinium is the ancient name of the blueberry and macrocarpon refers to the large fruit. Cranberry is a corruption of craneberry, the name colonist gave the plant because the flowers are shaped like the head and neck of a crane. The berries were so prized by the colonist that early Massachusetts’ history records a gift of l0 barrels of cranberries shipped to King Charles II. Because the berries remained on the shrub throughout the winter and also could be stored for up to a year, they were a very important staple in the diet of Native Americans also, and it is commonly thought that they introduced the pilgrims to the preparation of the fruit on the first Thanksgiving. They also used the berries that they called atoca, meaning “good fruit”, as a poultice for wounds, to cure stomach problems, as a diuretic, to lower fevers and to barter for food.
Description: American cranberry is a small, 6-8”, low growing evergreen shrub with slender, horizontal trailing stems which intermittently root at the nodes forming a mounding, dense groundcover of indefinite spread. The fine textured, evergreen leaves are simple, alternate, elliptic, entire and glabrous about l/2 to 3/4” long and not quite as wide. Their color is lustrous dark green in spring and summer, purple to burgundy, fall through winter. The horizontal stems are vegetative only, while the upright stems that grow from the leaf axils of the runners bear the small, bell shaped, pale pink flowers that look like miniature shooting stars. The blooms that start in May in the Atlanta area and go on intermittently throughout the summer are too small to be showy, but the recognizable red berry is very ornamental, starting out green in the summer, ripening in September-October to a rich, shiny red just in time to make it to the dinner table by Thanksgiving. Those that don’t, persist through the winter.
Cultivation:: Cranberries grown as ornamentals require much less exacting cultivation than the carefully produced commercial cranberry. You would expect it to require wet soil since it occurs naturally in bogs. Not so. The natural bogs are typically very wet with the spring rains but dry out in the summer and fall. Georgia has typically this same weather pattern. At the DeKalb College Botanical Garden we have found in the last three years that the cranberry shrub requires no more supplemental water than any other garden plant. What is does require is rich, organic, acid soil, full sun to very light shade and room for the runners to spread. We plant it in pure compost and add organic matter each year to keep the soil loose, rich and acid. By mulching with pine straw or bark, it can be kept as a 2-2 l/2’ shrub with the runners gracefully trailing on top of the mulch. For best results as a spreading ground cover forgo the pine straw or bark and allow the stems to root at the nodes spreading indefinitely. Plant it in the fall or early spring and treat it as any other shrub, giving it ample water until it is established. The speed by which it spreads can be hastened by fertilizing at regular intervals during the growing season.
Propagation:: While American cranberry can be grown from seed that has had a three month cold stratification period, cuttings are so easy and dependable that this is the usual method of propagation. To root it in a greenhouse environment, snip 6-l0” runner tips in late spring or summer, strip the bottom half of the tips of its foliage, dip in a rooting hormone and stick in sand or potting soil. Rooting usually takes place within a month. A handful of stems can be rooted altogether in the same hole. To root directly outside, use this same method. In late spring or early summer, gather a hand full of runner tips 8-l0” long, use a rooting hormone (dip and grow works fine), stick the whole handful in rich, moist, organic soil amended with creek sand and keep moist until roots are established.
Garden Use: The trailing stems of American cranberry which intermittently root at the nodes make it a natural for covering banks or any area where an evergreen low growing groundcover is needed. Plant it in masses or groups of 3-5 to edge a walk or driveway. Use it in front of course big leaf hollies or laurels for contrast. The horizontal growth habit of American Cranberry planted in front of the red upright ‘Rosy Glow’ Barberry is very interesting. Plant it near a Loropetalum ‘Burgundy’ to enhance the winter color of both. great in a rock garden or as an edging in a herb garden. Use it in containers alone or, even better, use it as the spilling edger in a large accent container filled with tall flowers or a shrub. The shiny dark stems trailing from a white window box in a sunny window would be gorgeous. Plant them as a crop around the perimeter of a vegetable garden to spruce it up. Wherever you plant it be generous and plant enough for you and the birds to enjoy.
Sunlight Gardens Georgia Perimeter College Native Plant Botanical Garden 174 Golden Lane 3251 Panthersville Road Andersonville, TN 37705 Decatur, GA 30034 (423) 494-8237 (678) 891-2668
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Radford, et al. 1968. Manual of the Vasular Flora of the Carolinas. U of NC Press, Chapel Hill, NC.