Prepared by George M. Dickert. Horticulture Extension Agent, Spartanburg County, Clemson University. (New 08/09.)
Although wild gingers, Asarum and Hexastylis species, can be found the world over, most of the ones that are cultivated for their ornamental value are native to the shaded woodlands of Asia and North America. Wild ginger does not refer to the culinary ginger (Zingiber officinale) that is used in stir-fry and ginger ale. However, its fleshy root does have a spicy aroma and can be substituted for culinary ginger in your favorite Asian recipe. The number of species and cultivars offers gardeners a wide choice of leaf patterns and color for use in a shade garden. These perennials are a versatile, easy-to-grow choice for the woodland shade garden as a groundcover or massed planting with outstanding foliage interest.
Large flower heartleaf wild ginger.
James Henderson, Gulf South Research Corporation, www.forestryimages.org
Most of the wild gingers grow 6 to 10 inches tall and spread 12 to 24 inches wide, depending on the species. The wild gingers are noted for being vigorous groundcovers that spread by rhizomes, or underground root structures. Their heart-shaped leaves grow on 4 to 12 inch-long stems that rise in pairs from the rhizome.
Wild gingers are noted as having slow to moderate growth, and therefore are not considered as being aggressive or invasive in their growth habit. However, if conditions are highly favorable, the plants can spread rather quickly and vigorously.
Wild gingers are primarily grown for their sensational foliage effects. The spring flowers, usually present in mid-to-late spring, are interesting, but are not particularly showy. The flowers are brownish red to purple, cup shaped, and consist of three united sepals, commonly referred to as “little brown jugs”. The flowers are rarely seen, as they are located beneath the foliage. They are pollinated by ants and other small, crawling insects.
Wild gingers can be used as a groundcover under trees and in front of taller plants in larger plantings. They look great with evergreen shrubs and/or wildflowers in a naturalistic setting. Wild gingers lend handsome variation to the shade garden. These plants thrive in full to partial shade, and will burn if planted in full sun. Wild ginger prefers a humus-rich, acidic, moist, well-drained soil for optimum growth. The plant can be divided in early spring by slicing the rhizome which grows close to the soil surface. The plants can also be propagated by seed, but it takes two years for germination. Most wild gingers are well suited to South Carolina summers if sited properly.
The wild gingers are members of the Aristolochiaceae, or the Birthwort family. These plants are typically divided into two genera: Asarum and Hexastylis. There are several species of Hexastylis and one species of Asarum found to occur naturally in the mountains, piedmont and coastal plain South Carolina. In North America, the native Asarum spp. are deciduous and the native Hexastylis spp. are evergreen.
Canadian Wild Ginger (Asarum canadense): This native species is known for being an aromatic, vigorously growing, ground-spreader. Its heart-shaped, light green leaves grow on 4- to 12-inch-long stems in pairs from the rhizome. This species is deciduous and hardy in Zones 3-7. This species of wild ginger is increasingly being planted by gardeners for use as a low maintenance groundcover for the shade or woodland garden.
Soft heart shaped leaves of Canadian wild ginger.
Photo courtesy of Wild Ginger Farm www.wildgingerfarm.com
Flowers of Canadian wild ginger, known as “little brown jugs”
George Dickert, ©2009, Clemson Extension
Arrowleaf Ginger(Hexastylis arifolia): This evergreen species is native to the woodlands of eastern North America and is common throughout South Carolina in moist, deciduous forests. As the name suggests, it has a distinct arrow-shaped leaf and has a growth habit similar to European wild ginger. There is a lot of variability in leaf color within this species. The leaves may be mottled with silver or entirely dark green. This species is hardy in Zones 4-8, and has cultural requirements similar to other ginger species.
Arrowleaf ginger is native throughout South Carolina.
Wendy VanDyk Evans, www.forestryimages.org
Large Flower Heartleaf(Hexastylis shuttleworthii): This wild ginger is well adapted to the southeast. It is a perennial, evergreen species that is hardy in Zones 5-8. It is similar to Canadian wild ginger, but it has thinner, mottled and usually larger leaves. The variety ‘Callaway’ is noted for being a slow-growing, mat-forming plant with silver-mottled leaves.
Other Native Wild Gingers: Less common native species with more attractive flowers are the Western wild ginger (A. caudatum), which is found in either purple flower or white flower forms, and the Alabama wild ginger (H. speciosum ‘Woodlander¹s Select’.
European Wild Ginger (Asarum europaeum): This introduced species is a vigorous ground-spreader that is widely cultivated. While it is similar to Canadian wild ginger, it is smaller in overall size (6 to 8 inches tall), has glossier green leaves and is hardy in Zones 4-7. Another factor that distinguishes it from Canadian wild ginger is that its foliage is evergreen, and therefore provides year-round interest. Its cultural requirements are the same as Canadian wild ginger, however this species is best planted in the mountains and piedmont of South Carolina.
Shiny, evergreen leaves of European wild ginger.
Karen Russ, ©2009 HGIC, Clemson Extension
Asian Wild Gingers: There are several desirable wild gingers from Asia that are starting to gain popularity in the U.S. for their ornamental value. The Japanese are avid collectors of these plants and have several societies dedicated to their study and use. The most commonly available Asian species grown in the U.S. is Hexastylis splendens. It has outstanding silver variegation on large heart-shaped leaves. The variegation is reportedly much more stable and defined than that of the North American natives. This species is said to be a slow grower compared to Canadian wild ginger and arrowleaf ginger. It is hardy in Zones 6 to 8. The cultivar ‘Quicksilver’ grows 6 inches tall and has large 6 inch-long, heart-shaped leaves that are silver mottled.
Many of the Asian wild gingers have larger and far showier flowers than most natives, especially the panda face ginger (Asarum maximum) and it’s cultivars ‘Ling Ling’ and ‘Green Panda’, and the Chinese wild ginger (A. delavayi) ‘Sichuan Splendor’.
Snails & Slugs: Wild gingers are prone to snail and slug damage in the early spring. These pests feed on wild ginger leaves and blooms at night. In a single night, their feeding can result in large, irregular holes in leaves and flowers. A sign of their presence is the slimy trail of mucus that they leave behind as they move. During the day, they hide under leaf litter, mulch and flower pots where it is moist. Snails and slugs are mollusks and thus related to clams and oysters. Like all mollusks, they must stay moist to survive.
Slug damage on Canadian wild ginger.
George Dickert, ©2009, Clemson Extension
Control: The first step in discouraging slugs and snails is to remove mulch and leaf litter near plants to reduce the moist conditions necessary for their survival. Slugs and snails can be removed by handpicking. The best time to look for them is a few hours after dark using a flashlight. Slug and snail traps can be made by filling shallow containers with beer and placing in a hole in the soil so that the rims are level with the soil. These pests are attracted by the yeasty smell and will fall in and drown. Before putting down the traps, water the area to encourage slug and snail activity that night. Placing a board on the ground, raised about one-inch, is another trap option. It provides a daytime hiding place for these pests that you can then lift to locate and dispose of them.
Protect plants by sprinkling diatomaceous earth around the plants. Diatomaceous earth is very sharp and scratches the skin of these soft-bodied critters, resulting in dehydration and death. It must be reapplied after a rain or watering New slug and snail control baits are available that contain iron phosphate, such as Sluggo, Escar-Go, Schultz Slug & Snail Bait, or Bayer Advanced Dual Action Snail & Slug Killer Bait. Iron phosphate will stop feeding by the snails and slugs quickly, and is much less harmful to pets, birds, and non-target insects than older baits containing metaldehyde. Any unconsumed iron phosphate bait adds nutrients to the soil. Consult the label for the specific crops it can be used on and also for information on the rate. Read and follow all label directions and precautions before use.
Examples of retail mail order sources of wild gingers:
Wild Ginger Farm
24000 S. Schuebel School Rd.
Beavercreek, OR 97004
11 species &/or cultivars
Plant Delights Nursery
9241 Sauls Rd.
Raleigh, NC 27603
11 species &/or cultivars
174 Golden Ln.
3 species &/or cultivars
Shady Gardens Nursery
6545 Old West Point Rd.
LaGrange, GA 30240
1 species &/or cultivar
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This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.