Several different plants are called ginseng, but the wild ginseng native to North American forests, also called Panax quinquefolius, is the species that has been used medicinally for many years. According to Purdue University, the U.S. Food and Drug Administration classifies ginseng as a food rather than a drug and lists ginseng as "generally recognized safe." American ginseng grows wild in shady northern forests with rich, loamy soil. For successful growth, home gardeners must imitate this natural environment.
Fine, deep sandy loam is the best soil for ginseng, according to Washington State University and Purdue University because it provides the moderate permeability that ginseng needs. Soil that is rich in organic matter, up to 10 percent, promotes abundant growth of ginseng roots. Successful ginseng farmers in Ontario, Canada add up to 40 tons of cow manure to each acre of land before they plant ginseng seeds, and then they allow the manure to decompose for several months before planting time arrives in fall. Other good organic materials include wood shavings, sawdust, leaves or tree trimmings. Purdue University also mentions that growers should remove as many rocks from the soil as possible.
Washington State University advises ginseng growers to adjust their soil pH to measure slightly acidic, between 5.6 and 5.8. This reading is the same as ginseng's native forests in Appalachia. Growth will be slow if the pH is either higher or lower than the recommended level because the roots will not be able to absorb the nutrients this plant needs. Washington State also adds that the addition of ground limestone or dolomite to ginseng's growing area before planting will ensure that the soil remains acidic. If your soil is alkaline, mulching with sawdust can help to lower the pH, as will fertilizing with ammonium sulfate.
Ginseng roots can become rotted if the soil in which you plant the seeds has poor drainage. Soils such as coarse gravel or sand drain too quickly for ginseng, while heavy clay soil or clay loam retains too much water. For large planting areas, changing the drainage of soil can be difficult. Areas where water stands in ponds after a rain are not suitable environments for growing ginseng. Washington State University recommends that prospective growers closely examine land for its drainage characteristics during the wet season and choose another area if standing water is apparent. Growing ginseng on raised beds has helped many growers overcome poorly-draining soil.