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Ginseng culture on Pennsylvania forestlands

Biological Considerations

Vegetative

American ginseng is a perennial herbaceous plant, meaning that it grows for many years, but any aboveground portions (stems, leaves, etc.) do not persist over the winter months. As a plant ages, it progresses through a series of distinct stages (Figure 1). Since ginseng produces palmately-compound leaves in which each leaf consists of one to seven smaller leaflets arranged around a central axis, each of its stages are identified by the total number of leaves (rather than leaflets) on a plant. In ginseng trade, a palmately-compound leaf is commonly referred to as a prong. Through the course of development, the number of compound leaves increases. Thus, the stages in ginseng development are called one-prong, two-prong, three-prong, and so on, depending on leaf number.

Following germination, ginseng seedlings appear as small, three-leaflet (trifoliate) plants and remain in this growth stage for the entire first year. In subsequent years, the plants add leaflets, entire leaves, or both. Generally, the progression of vegetative growth is from seedling to one prong (with five leaflets); from one prong to two prongs (with ten leaflets); from two prongs to three prongs (with fifteen leaflets); and from three prongs to four prongs (with twenty leaflets). This progression may occur on an annual basis, or the plant may take many years to evolve from one stage to the next. older ginseng stages are considered to be the three- and four-prong stages. It is rare to encounter more leaves than this on a plant, although five- , six- , and even eight-prong plants, for instance, have been documented from Pennsylvania forestlands.

While distinct growth stages are characteristic of ginseng development, they do not necessarily reveal the plant's specific age. For example, it is common to find old plants in the forest that are only in the two-prong stage and young plants that are in the four-prong stage. Many ginseng plants cultured under forest conditions attain the three-prong stage by the fifth year; however, the rate at which an individual plant proceeds through the vegetative stages of growth depends on the favorability of the site and climate. Under the best cultural conditions, plants attain more advanced growth stages in as little as four years. Given less favorable conditions, it may take as many as thirty years for plants to develop three or four prongs.

The ultimate stage a plant attains is largely irrelevant in ginseng commerce; the age and appearance of the root are most important. Therefore, you should not become preoccupied with growing the "biggest" plants if root production is the primary goal. If, on the other hand, you are interested in seed production or establishing self-seeding populations, then it is desirable to encourage the rapid development of advanced stages because ginseng does not begin to flower (and fruit) until the two-prong stage. Advanced stages, such as three- and four- prong, contribute the most to population maintenance and growth through their relatively greater fruit and seed production. As a result, it is advisable to leave a number of these "seed plant" stages when harvesting wild-simulated plantings to ensure a supply of seeds.

Further information about ginseng biology and growth stages

Flowering and Fruiting

In Pennsylvania, the flowering period begins in early to mid-June and continues through mid-July. Flowers are clustered, and each flower is small with the potential to develop and ripen into a bright red drupe. In the ginseng trade, these fruits are referred to as berries or seed pods and mature during August and September. Ginseng is known to be both self- and cross-compatible, which means that plants do not need to be cross-pollinated for fruits and seeds to develop, although the process is beneficial for adaptation to changing conditions over time.

Germination of ripened seeds requires eighteen to twenty-two months on average. During the process of seed dormancy, seeds must remain moist (not wet) and must be exposed to alternating cycles of cold/warm (simulating winter-summer cycles). If one or both of these stratification requirements is not met, seed viability and germination will be low and unpredictable.

Site Selection

Forest farming of native medicinal plants such as American ginseng requires an appreciation of how the over-story (the trees) influences the under-story (the crop). With forest farming, the tree canopy should provide a favorable microclimatic and nutrient-cycling condition for plant establishment, growth, and reproduction. Locating the appropriate habitat is critical to success.

American ginseng is an adaptable plant that tolerates a wide variety of forest conditions. However, the best growth is obtained under a specific set of conditions. For example, ginseng is shade-obligate and requires tree and/or shrub coverage of approximately 60 to 90 percent shade. Under relatively low-light conditions (e.g., 90 percent shade), growth and development may be slow and fruit and seed productivity may be low. On the other hand, under relatively high light conditions (e.g., 60 percent shade), growth rate and productivity may be high-perhaps too high since rapid development can result in roots that have less desirable commercial appearance (i.e., they look "cultivated").

Similarly, the soil's specific physical and chemical attributes associated with wild ginseng growth in Pennsylvania vary considerably. Both historical and contemporary documentation of ginseng across Pennsylvania support the notion that the plant may thrive on a variety of soil types. In general, soils that appear most conducive to ginseng culture tend to be loamy, moist, high in organic matter, and slightly acidic (i.e., having a pH of 4.5 to 6.0). Research indicates that high calcium levels (e.g., more than 1,000 lbs per acre) may also enhance ginseng survival and productivity.

It is often the case that the best locations for establishing American ginseng plantings or gardens will be in terrain with a northern and/or eastern aspect. Aspect refers to the compass direction toward which a given topographic feature (e.g., hill or mountainside) is oriented. Aspect largely determines the duration and intensity of sunlight exposure and these, in turn, dictate temperature and moisture regimes in an area. In Pennsylvania, a north- or east-facing hill or mountainside will generally be cooler and moister than a south- or west- facing one since the latter receives more direct sun. Variations are common, such as when a mountainside faces south yet a drainage cutting through it contains northern/eastern-oriented micro-aspects. These "pockets" can be excellent locations for establishing ginseng plantings, even though the overall aspect of the area is not correct. Generally, such micro-aspects are recognizable because they differ in vegetation from the surrounding areas.

One of the most convenient and reliable methods for locating favorable ginseng habitats is looking for so-called indicator species, which are trees and plants that tend to grow in association with ginseng on forested sites. Table 1 gives the different trees, shrubs, herbs, and ferns that are often associated with ginseng in Pennsylvania-both in the wild and where successful introductions have been made. This information is drawn from field research conducted around the state over the past several years, as well as from grower and collector accounts. It is important to recognize that both over-story and under-story indicators are important in evaluating a potential growing site. Choosing a location based solely on one (e.g., trees) or the other (e.g., herbs) is far less reliable.

Keep in mind that while the use of indicator species is helpful, the specific plants used to identify favorable growing sites for ginseng will vary somewhat from region to region across the state. It is recommended that you experiment in a number of locations on your forestland to discover favorable areas and reduce the possibility of failure due to placing "all your eggs in one basket."

Ginseng Propagation

The planting of ginseng seed on Pennsylvania forestlands has been a common practice for at least a century; as a result, whether a given plant is truly "wild" is always open to question and speculation. Nevertheless, there are genetic considerations to keep in mind when "commercial" seed is used for planting efforts ("commercial" seed is purchased seed that originates from a nursery or farm-produced at a location distant from the planting site).

In practice, forest farmers should strive to maintain or increase genetic diversity in American ginseng. Where wild plants or populations already occur, it is best to use these preexisting plants for growing stock rather than introduce commercial sources into the area. Cross-breeding following the introduction of "non-local" genes could have adverse consequences such as the loss of any adaptive genetic characteristics present in local populations (e.g., disease resistance). Where there are no preexisting plants, and "commercial" stock is therefore the only option, you should seek out local or regional nurseries or farms. From a practical standpoint, the planting of locally or regionally sourced stock may prove more successful since it is generally going to be better adapted to the regional climate.

Ginseng may be grown or propagated from seed, from transplants grown from seed, or, less commonly, from root division (i.e., dividing the "neck"). The simplest and most economical method is propagation from seed since this method requires less time and labor and cost than root division and the results are more predictable.

Whether the seed originates from a local forestland or from a distant supplier, ginseng seed requires stratification before it will successfully germinate. Seed stratification in ginseng means that the seed is exposed to alternating periods of cold and warm temperatures over twelve to sixteen months in a manner that replicates seasonal temperature patterns. Most commercial seed suppliers sell only stratified seeds eliminating the need to stratify; however, collected seed must either be planted immediately or stratified if planting is to be delayed for an extended period. Perhaps the most important thing to remember in either case is that ginseng seed must never dry out; it needs to be kept moist at all times or viability is reduced.

Two- or three-year-old ginseng transplants, or rootlets, are grown from seed by commercial suppliers for transplanting into forestlands. The advantages of using transplants are that they reduce the production period and growers can better anticipate plant spacing. The biggest disadvantage is the higher cost. When compared to the cost of seed, transplants are much more expensive at $0.50 to $1.50 per root. If you are just starting out, it may be desirable to purchase a mixture of both seed and transplant materials in order for you to realize the advantages of using transplants without incurring large initial investment costs.

A third method for propagating ginseng is to divide the root or rhizome. Ginseng collectors have often propagated plants by separating the rhizome, or "neck," from an existing root and replanting it. While this method is not entirely reliable, research has demonstrated that vegetative propagation by root division is indeed successful much of the time. the largest obstacle to the broad use of this method is a federal requirement that the neck be retained on root sold to buyers because it is used to age the root. Also, because root age is important with respect to its market value, an intact root is also favored by buyers. Thus, while propagation by root division is appropriate for some purposes, such as increasing numbers of genetically identical plants for seed production, it is not recommended if your sole objective is to produce root that is legally and economically acceptable.

Approaches to Ginseng Forest Farming

In ginseng forest farming, there are two approaches: (1) the woods-cultivated approach and (2) the wild-simulated approach. The woods-cultivated approach generally requires more labor and time because it involves more intensive production techniques, such as the use of raised beds, fertilizers, and pesticides. The wild-simulated approach follows a less-intensive strategy that may involve nothing more than planting seed in suitable locations. Depending on grower objectives, both approaches can be useful in forest farming. Moreover, the distinction between these two approaches is one of convenience; your approach may involve elements of both.

Woods-Cultivated Ginseng

The woods-cultivated approach takes advantage of the natural forest ecosystem for shade and microclimate, but it also modifies under-story site conditions to provide a more favorable habitat for plant establishment and management. This approach usually involves more investment in equipment, materials, time, and labor than the wild-simulated approach. A common component of the woods cultivated approach is the use of raised growing beds. Raised beds allow for concentrated plantings around which establishment and maintenance activities are centered. the woods-cultivated approach is often used to establish plantings that provide a source of seed or transplants for wild-simulated stocking efforts.

Before creating raised beds, it is wise to consider the suitability of the terrain for such "improvements," especially if you plan to use farm or garden equipment. For example, beds should not be situated on slopes that would compromise safety or ecological integrity (e.g., the potential for soil erosion). Similarly, areas where many tree roots or large rocks occur at the soil surface are difficult for intensive cultivation since they can create difficult and hazardous conditions for the use of mechanical equipment.

A simple way to create a raised bed is to till or dig an area slightly larger than the desired bed width and use the outside soil to build up or hill the center. For instance, to create a raised bed with a desired width of four feet, you would till or dig an area six to eight feet wide and use the outer one or two feet, respectively, of loosened soil to mound the center of the four foot-wide bed. The additional soil is necessary to create a rounded or domed bed, which will allow the bed to shed excess moisture more readily during a rainstorm. Ginseng plants are extremely susceptible to a number of fungal diseases where moisture or wet conditions persist.

Once the bed is shaped, the soil can be amended as desired with limestone (for pH adjustment), gypsum (to supply calcium), or organic amendments such as well-rotted sawdust or compost. If a fertilizer is applied, it should be a low-analysis fertilizer (e.g., 5-5-5) since heavy fertilization can encourage disease problems as well as a final product that looks "cultivated."

Raised forest beds can be seeded at any density, but roughly one or two years after seeding, plants should be thinned to one or two plants per square foot or less. If seed production is the primary goal, wider spacing is desirable to encourage plant productivity and simplify berry harvesting. If transplant production is the goal, seedlings should be maintained in dense plantings until about the third or fourth year, at which time they can be transplanted. It is not advisable to maintain dense plantings beyond the fourth year of growth because fungal diseases almost always begin to appear by this time. Nor is it advisable to transplant first-year seedlings since they are often too fragile to endure the stress of handling and relocation.

The woods-cultivated system's primary advantages are that plant and root growth are hastened and cultivation is convenient and organized. The main disadvantages of this approach are its high incidence of disease problems and greater investments in materials and labor. Also note that if your goal is root production, as opposed to seed or transplant production, the ultimate return on the investment depends largely on the ability to manage the crop so that the final root appears "wild" rather than "cultivated." Woods-cultivated root can be discerned on the market by experienced buyers, and its value can be well below wild or wild-simulated product value.

Wild-Simulated Ginseng

The wild-simulated approach to growing ginseng involves thinly sowing seeds in the forest and leaving them to grow with minimal human influence. In this approach, the goal is to establish and maintain "wild" populations. This approach is the easiest and least expensive to follow, but it is also the slowest and, perhaps, most unpredictable. Depending on your preference and motivation, this approach may involve little care or maintenance, and the chief investment will be seed for planting. With wild-simulated plantings, the importance of forest-site selection cannot be overstated.

Once a promising location has been identified, some of the vegetation from the forest area(s) may be thinned before planting. The objective is to remove any potentially interfering plants without adversely altering the site's quality and ecology. You may choose to remove any undesirable over-story or under-story trees and shrubs to keep with the overall forest management goals and plans. Exercise caution because removing too much of the over-story or under-story may expose the location to too much sunlight. It may also increase germination and competition from other plants. Any thinning should seek to maintain about 65 to 70 percent shade in the vicinity of ginseng plantings.

Little or no soil preparation is required in the wild-simulated approach, nor are there raised beds. Instead, seeds are sown by (1) individually hand-planting by pushing seeds about one inch deep into the mineral soil; (2) brushing aside leaf litter with a rake, scattering seed, and then replacing the leaf litter; and/or (3) using a specialized seed planter such as a seed spreader or "seed stick" (hand-held, jab-type planter with an attached hopper). If done properly, all of these methods create minimal disturbance to the forest environment and can easily be accomplished without much expense. Methods that require more individual care per seed (such as hand-planting) will require more time, but this care also tends to improve seed survival and establishment success.

Ideally, seed planting is done in autumn just before leaf fall; however, planting can extend from late summer through early winter. Although the plants should ultimately be grown at a low-density spacing to reduce the potential for disease problems, the initial seeding rate can be relatively high since many seedlings will be lost over time. For example, while the final spacing may be roughly one plant per one to three square feet, the initial seeding rate may be as much as four seeds per square foot. In general, you should expect to lose one seedling per year for the first three years following establishment. Where seedling survival is great, plants are moved or thinned as desired.

After planting, wild-simulated plantings are left to "Mother Nature" and thinning and culling generally occur naturally. Any weeds or undesirable plants that appear after planting can be thinned periodically to reduce competition, but avoid the use of herbicides and fertilizers. Additional seeds and seedlings can be planted, perhaps yearly, to ensure a continuous harvest and to replace any seedlings lost to slugs or other pests. On favorable sites, additional seed and seedling recruitment is likely to come from existing plants as they attain reproductive age. Tending these patches by planting berries and seeds will help ensure continuous recruitment and a perpetual harvest.

The wild-simulated approach to growing ginseng has several characteristics that make it especially attractive as a forest-farming venture. First, there is no need to invest large amounts of money or labor. Second, there is a noticeable decline in the incidence of disease in such plantings, thereby virtually eliminating the need for pesticides (an important benefit for those seeking organic certification). Third, the price-per-pound returns for wild-simulated products are generally greater than for woods-cultivated products due to the often "wilder" appearance. Finally, this approach has little or no impact on the forest ecosystem, and you can, therefore, utilize the forest while conserving it at the same time.

The main disadvantages of the wild-simulated approach are the unpredictable results that can come from simply scattering seeds in the woods and the length of time required to obtain harvestable products (often as long as nine to ten years). However, these challenges practically ensure a strong market for such products and, thus, a place for the patient forest farmer as a supplier.

This web content is adapted from Forest Finance series #5: Opportunities from Ginseng Husbandry in Pennsylvania (Burkhart and Jacobson) published in 2007 by the Pennsylvania State University (copyrighted 2007).

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