American Ginseng Cultivation & Growing Guide.

Originally published in The Forest Farmers Handbook: A Beginners Guide to Growing and Marketing At-Risk Forest Herbs by United Plant Savers & Rural Action (available here).

Overview

ginseng
(Panax quinquefolius)
Araliaceae

American ginseng (Panax quinquefolius) is a long-lived perennial herb that is native to the deciduous forests of eastern North America. Due to its high value, which can range from $600 to more than $1,000 per dried pound, American ginseng has been over-harvested throughout much of its natural range. Intense harvest pressure on wild populations has been further compounded by low reproductive rates, limited seed dispersal, and high seedling mortality. Ginseng roots vary in size and shape and are considered the most valuable part of the plant, although medicinally active “ginsenosides” are present in the leaves, stem, flowers, flower buds, and seed pulp (Qi et al., 2011). American ginseng is highly valued in Asian markets due to a close resemblance to Asian ginseng (Panax ginseng), which has been used in traditional Chinese medicine for over 2,000 years (Bergner, 1996). In response to demand from Asian markets, ginseng became one of the early commodities exported from eastern North America and the United States (ca. 1717-1784). Due to concerns about the impacts of harvesting on wild populations, the commercial harvest, sale, and export of ginseng roots has been regulated since 1975 after the species was listed in Appendix II of the Convention on the International Trade of Endangered Species of Wild Flora and Fauna (C.I.T.E.S) (Burkhart et al., 2012). Under CITES, the harvest, sale, and export of wild ginseng is regulated and monitored at both the State and Federal level to ensure that the commercial trade in ginseng roots is not detrimental to the survival of the species (Robbins, 1998).

Life Cycle

Ginseng is a slow-growing species, advancing through a single stage of development each year by adding one new set of compound leaves (Mooney and McGraw, 2009), which is commonly referred to as a “prong” among the ginseng community. After germinating, plants typically persist as seedlings for one to two years and then begin to progress through one-leaf, two-leaf, three-leaf, and four-leaf stages of development over time (McGraw et al., 2013), as illustrated in Figure 9. Progression through these developmental stages is variable, with plants being capable of persisting in juvenile and seedling stages for several years or reverting to lower stages of development in response to environmental factors (e.g. drought, herbivory, etc.) (McGraw et al., 2013). Ginseng has a long pre-reproductive period and does not typically reproduce until after 5-6 years of growth, and the three-leaf stage of development has been reached (Mooney and McGraw, 2009), although some seeds may be produced by two-leaf plants (Obae and West, 2011). Ginseng seeds have a functionally underdeveloped embryo when they ripen on the plant and require 18 months of stratification before they will germinate.

Pollination and Seed Development

ginseng2Ginseng flowers typically bloom from late June through mid-July and are pollinated by syrphid flies and halictid “sweat” bees, which are generalist pollinators that visit many species of forest plants (Burkhart and Jacobson, 2004). Ginseng plants are also capable of self-pollination, which is a common occurrence when populations are widely dispersed and reproductively isolated. When it occurs, cross pollination contributes to gene flow and genetic diversity among populations and has been found to result in the production of larger plants (McGraw et al., 2013). After pollination, the seeds will develop through the summer months and ripen from late August through September. The “berries” are covered with a fleshy pulp that turns from green to red when ripe. Each “berry” contains 1-2 seeds, which simply fall from the plant if they are not eaten by deer, chipmunks, squirrels, birds, or other frugivorous critters. Recent research has discovered that the wood thrush (Hylocichla mustelina), a neotropical migratory songbird that breeds in the hardwood forests of the eastern United States, is one of the few long-distance dispersers of American ginseng seeds and have been observed to move seeds 20-30 meters from the parent plant before depositing them in their new location. (Hruska et al., 2014, Elza et al., 2016).

Ginseng Propagation

Propagation from Seed:

To improve the chances for successful germination, seeds should be collected after the pulp has turned completely red. Seeds that are collected while the pulp is still green tend to have lower rates of germination or may fail to germinate at all (McGraw et al., 2005). The seeds should be collected as soon as possible after ripening in order to prevent potential losses to animal predation. After collecting, the seeds can be planted directly, or they can be cleaned and stored in a stratification box for up to 1 year. For direct planting of freshly collected seeds, crush the berry pulp between your fingers to retrieve the seeds, and then plant them individually in holes ½” – ¾” deep. The seeds will stratify naturally and should germinate two years after planting.

Seed Stratification:

Stratifying your own seeds can be a tricky process, but it may be worthwhile if you are able to collect a relatively large quantity of seeds from your plantings. As previously discussed, stratification is simply a process where seed dormancy is broken in order to facilitate germination. This is typically accomplished by placing ginseng seeds between layers of coarse-grained sand, and then burying them underground in a stratification box for up to 1 year. The stratification box should be constructed in a way that excludes pests and rodents but still allows water to percolate through the layers of sand and seeds. This is generally accomplished by constructing a box with solid sides and sturdy wire mesh screens on the top and bottom. The porous sand mixture will help keep the seeds moist, while preventing water from accumulating in the box and causing them to rot.

Before the seeds can be stratified, they need to be removed from the pulp. To de-pulp, place the berries in a bucket of water for approximately 12-24 hours to help loosen the pulp from the seeds. Discard the water, and then rinse repeatedly with a medium pressure hose to dislodge the remaining pulp. Before placing the seeds in the stratification box, spread them on a fine mesh screen or drying rack and allow them to air dry to remove excess moisture.

Stratification boxes should be buried to a depth where the top of the box is 8” beneath the surface of the soil (Davis and Persons, 2014). Boxes should always be placed in well drained soils to ensure proper drainage and that water does not accumulate in the hole. Boxes may also need to be periodically pulled up during the stratification process to monitor moisture levels and to check for potential spoilage.

Propagation from Root Cuttings:

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Figure 1

In some cases, “neck division” or “neck replanting” may be a viable way to propagate ginseng roots but will ultimately depend on how the roots will be processed and sold. Roots that are destined for export markets, or that are intended to be sold as whole and in-tact roots, are not good candidates for neck propagation. But lower-grade roots that are more likely to be processed into root powders and extracts can be very good candidates for neck propagation. As illustrated in figure 10, an ideal cutting will include the root neck, the terminal bud, and one or two small fibrous roots. Simply sever the neck cutting from the main tuber using a sharp clean utensil. Plant the cutting on its side at a 30° angle and 1½”- 2” deep. Based on experimental evidence, approximately half of the cuttings should be expected to emerge the following season (Beyfuss, 2017b).

Site Selection

Ginseng is typically found growing on north, northeast, and east facing aspects under a mature forest canopy that provides approximately 75%-90% shade (Davis and Persons, 2014). Within these baseline conditions, ginseng prefers sites with well-drained soils that are rich in organic matter yet maintain a slightly acidic soil pH (5.5–6.0) (Davis and Persons, 2014). Good soil drainage is essential for healthy ginseng plantings. Ginseng is susceptible to several species of water-borne pathogens, and the accumulation of excess water in the growing site can contribute to the spread of diseases that can decimate ginseng plantings. As we have previously discussed, planting sites with gentle to moderately sloped terrain will help facilitate soil drainage and can go a long way to helping keep your ginseng plantings healthy.

The presence of certain companion plants and other indicator species can also be used to identify and evaluate potential production sites. Species that are commonly found growing in association with ginseng, include, but are not limited to, tulip poplar, sugar maple, basswood, black walnut, red oak, slippery elm, white ash, spicebush, trillium, black cohosh, blue cohosh, goldenseal, Jack-in-the-pulpit, maidenhair fern, rattlesnake fern, and bloodroot (Apsley and Carroll, 2013; Burkhart, 2013).

Soil calcium content has been shown to be highly beneficial to the growth and development of ginseng plantings, contributing to increased root growth and disease resistance (Hankins, 2000). Evidence suggests that ginseng plantings thrive in soils with calcium levels ranging from 2500–5000 lbs/acre (Beyfuss, unpublished). Many of the species listed above, such as, tulip poplar, sugar maple, Jack-in-the-pulpit, rattlesnake fern, and maidenhair fern (Burkhart, 2013), are all calcium loving species and can help you identify calcium-rich production sites. Phosphorus, which is used by plants to absorb and process calcium, is another important factor to consider during the site selection process. Phosphorus levels of 90 lbs/acre are recommended and can be augmented by supplementing with rock phosphate (Hankins, 2000).

Wild-Simulated Site Preparation

To prepare the growing site for a wild-simulated planting, start by removing any fallen branches, rocks, or other debris that will interfere with the planting process. These can be staged adjacent to the planting site and can be thrown back on after seeding to help hold the leaf litter in place. If necessary, selectively remove small trees and shrubs, or prune low hanging branches to improve airflow and optimize light conditions. If invasive species are present, they should be manually removed and/or controlled prior to planting. Native understory plants should be left in place to help maintain a diverse polyculture of plants, which will also help to limit the spread of pathogens (Hankins, 2000).

Planting Seeds Using the Wild-Simulated Method

Whether collected and stratified yourself, or purchased from a commercial supplier, ginseng seeds should be planted in the fall of the year as temperatures begin to cool, and when there is adequate moisture to ensure that seeds will not dry out after planting. Seeds can be planted anytime during the fall months, but it is best to plant just before peak leaf drop, which helps to ensure that the seeds will be well insulated by the layers of freshly fallen leaves.

Working across the slope, rake the leaf litter downhill to create wild-simulated “beds” that are approximately 4’-5’ wide and up to 50’ long. After the leaves have been cleared, scuff the surface of the soil with a hard steel rake to loosen the top ¼” of material. From the uphill side of the bed, broadcast seeds at a rate of 5-7 seeds/sq. ft. and even disperse across the bed (Apsley and Carroll, 2013, Davis and Persons, 2014). After seeding, move uphill and prepare to make a second bed. Rake the leaves from the second bed downhill to cover the previously seeded area, covering the bed with approximately 1-2 inches of leaf litter. Simply repeat the process until the site has been fully planted.

Planting Rootlets

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Figure 11

Ginseng plantings can be started by transplanting young rootlets but require more financial investment when compared to seeds, and the survival of transplants can be highly variable. Transplanted roots and/or rootlets should be planted approximately 2”- 2½” deep with the terminal bud approximately 1” – 1½” beneath the surface of the soil. Rootlets should be planted on their side at a slight angle (approx. 30° angle) with the fibrous roots spread laterally. After planting, backfill with the removed soil and re-covered with approximately 2” of leaf litter (Bennett et al., 2011).

Maintenance

Plantings should be regularly inspected for signs of disease and evidence of other disturbances, such as predation by common pests, or signs of unwanted trespassing and/or poaching. As previously noted, the amount of crop maintenance will depend on the intensity of site preparation and the extent of site modifications. For wild-simulated and woods-cultivated plantings, periodic thinning/pruning of competitive vegetation may be needed to maintain an open growing site, as well as light weeding. If plants fail to thrive in a particular growing site, the addition of beneficial nutrients may be required, such as pelletized gypsum to boost calcium concentrations (Hankins, 2000), and composted leaf mulch to increase organic matter.

Pests

Deer:

Whitetail deer have been identified as one of the main threats to the long-term viability of wild ginseng populations (FWS, 2016; Furedi and McGraw, 2004), and this threat holds true for forest-farmed plantings as well. Repeated browsing can cause decreases in root mass, loss of seed production, as well as contributing to prolonged periods dormancy or even death. Addressing deer problems can be a difficult and potentially costly intervention. Electric and non-electric fences, natural barriers, and other protective structures will all help to reduce the frequency of deer browsing and will have varying degrees of efficacy. Active hunting and agricultural nuisance permits can also be an effective means of controlling deer populations on and around your property.

Mice, Moles, and Voles:

Mice, moles, and voles are rarely seen but can cause significant damage to ginseng crops by consuming roots, de-hulling and destroying seeds, and severing the base of the stem from the root. Commercially available baits and traps can be an effective way to reduce the number of these critters in your production site, but significant care should be taken to protect baits/poisons from the elements in order to prevent contamination of the site, and consumption by non-target wildlife.

Slugs:

Slugs primarily feed on ginseng leaves and can cause significant mortality among first-year seedlings. Organic controls such as homemade beer traps and surrounding plants with diatomaceous earth are both effective means of control (Scott et al., 1995). Commercial slug repellents are also available, but care should be taken when applying these products in order to prevent contamination of plants or the growing site.

Diseases

Ginseng is susceptible to a variety of fungal pathogens that can potentially destroy an entire planting if left unchecked. The first line of defense in disease control is prevention. By selecting good growing sites and maintaining healthy growing conditions, such as ensuring that there is adequate airflow and maintaining planting densities of 1-2 plants per sq. ft., the potential for disease outbreaks can be significantly reduced. Planting or maintaining a diverse polyculture of species can also help prevent the spread of pathogens (Apsley and Carroll, 2013). Learning the signs and symptoms of common ginseng diseases is strongly recommended.

Alternaria Blight:

Alternaria leaf blight, caused by Alternaria panax, is one of the most common fungal diseases found in ginseng plantings. Infected leaves will display patchy, yellow/tan, bullseye-shaped lesions that will ultimately defoliate the plant. Leaf blight is not typically fatal in mature plants but will stunt growth (Beyfuss, 2017). If Alternaria is present, care should be taken not to spread the spores between sites. The fungal spores overwinter on infected leaf material and will continue to re-infect plants the following season. Therefore, the leaves from infected plants should be collected and removed from the site whenever possible to prevent reinfection (Vaughan et al., 2009).

Damping Off:

Damping off disease typically infects seedlings in the spring when conditions are cool and moist. The species of fungi that cause damping off disease live near the soil surface and attack seedling stems as they germinate and emerge (Apsley and Carroll, 2013). Seedlings that tip over and rot soon after germinating are common signs of damping off disease. Close examination of seedlings will show a tapering/constriction at the base of the stem where it has rotted away from the root (Beyfuss, 2017). Mature plants can typically resist damping off, but seedlings will likely die once they have been infected.

Phytophora Root Rot:

Root rot disease occurs less frequently than other pathogens (e.g. Alternaria) but is considered one of the most serious and deadly ginseng diseases. Root rot tends to infect mature plants in the 3-4 years old age classes and can arise very rapidly. The leaves of infected plants will appear to spontaneously wilt and discolor (turning yellowish/red) in a very short period of time, signaling the ultimate demise of the plant. Infected plant material, and potentially the soil from immediately around the root, should be removed to prevent the spread of the disease. If the roots have completely disintegrated by the time the disease is noticed, the hole that the plants were growing in should be sterilized with a bleach and water solution (1 cup bleach/per gallon water). Similarly, any tools used to remove infected plants or soil should be sterilized to prevent reinfection (Beyfuss, 2017). The good news is that many of the disease problems listed above can be virtually eliminated in a wild-simulated setting by taking the time to select optimal growing sites and following the wild-simulated planting guidelines provided in this handbook.

Harvest Regulations

By law, “wild” ginseng roots cannot be legally harvested before September 1st or before they have reached 5 years of age. Most states that have active ginseng management programs do not make any distinction between wild and wild-simulated roots, leaving wild-simulated growers subject to the laws that have been developed to regulate “wild” ginseng. Fortunately, this is not a significant obstacle for wild-simulated producers to overcome, since wild-simulated roots are not typically harvested until after 7-10 years of growth and are harvested in the fall of the year. It is important to familiarize yourself with any relevant State and Federal regulations governing the harvest and sale of ginseng roots to ensure regulatory compliance. You should also contact your State Regulatory Agency to address any questions that you might have.

Harvesting Roots

Ginseng roots should be harvested in the fall of the year after all seeds have fully matured, and the leaves have begun to turn yellow and die back. At this stage of development, root ginsenoside concentrations reach peak levels as medicinal constituents in the leaves are reabsorbed by the root system (Li, et al., 1996), thus helping to ensure a high-quality product. Ginseng roots are largely valued based on their appearance, and great care should be taken during the harvest process to preserve the physical qualities of the root. Roots can be harvested with a variety of tools, including spade forks, soil knives, and small or large mattocks. Regardless of the tool, it is important to select the implement that you are most comfortable with, and that can be used effectively without damaging roots. Digging should begin slowly and at least 6-10 inches from the stem to avoid breaking the fibrous roots that extend into the soil surrounding the plant (Vaughan et al., 2009).

Washing

Washing ginseng roots can seem somewhat counterintuitive because, unlike other species, having a small amount of residual dirt on the root is actually desirable, specifically between the dense growth rings on the root body. Roots should not be scrubbed clean with a brush, as they will have an unnatural whitish appearance and will typically result in a lower market value (Davis and Persons, 2014). The best way to prevent over-washing is to briefly soak roots in a bucket of water, and then rub them with your fingers to remove excess dirt and debris. When the roots are rubbed clean, a small amount of dirt is left between the dense growth rings on the exterior root and helps accentuate the roots’ wild characteristics.

Drying

Roots must be properly dried in order to preserve product quality and ensure the integrity of the product during long-term storage. To dry, spread roots evenly on a wire mesh screen in a dark, well-ventilated area with adequate airflow where temperatures can be maintained at 85-95F. In humid locations, temperatures above 100F may be needed to fully drive off excess moisture from the roots (Davis, 2016). The roots should be regularly inspected for any signs of mold or spoilage, and, if detected, the infected pieces should be removed from the room. During the drying process, roots will lose approximately   70% – 75% of their weight, and the color will darken slightly, turning from white/cream to light brown. While the exterior of the root may darken slightly, the inside of the root should maintain a whitish color. Roots that are dried too quickly can develop a dark “sugar” ring on the inside of the root, which can lower the root value (Vaughan et al., 2009). To determine when the drying process is complete, select several average-sized roots from the batch, and then break them in half. The roots should snap cleanly when fully dried but should not be overly brittle.

Ginseng roots can also be kept fresh for several weeks by storing them in the refrigerator. Fresh roots should be stored in a plastic bag with a moist paper towel that can either wick up excess moisture or release moisture to the roots when needed. Bags should be opened regularly to exchange fresh air and to inspect the roots for signs of spoilage.

Harvesting and Drying Ginseng Leaves

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Figure 12

Ginseng leaves also contain relevant concentrations of ginsenosides and may be a product that can help producers generate income while waiting for roots to reach a harvestable size/age. Leaves should only be collected from mature 3-prong and 4-prong plants, and it is recommended that at least 2 prongs be left on each plant in order to minimize any negative effect on root growth. Leaves should be collected between July and August when ginsenoside concentrations are at peak levels (Li et al., 1996, Li and Wardle, 2002).

Ginseng leaves can be dried using the same technique previously described for roots but can be successfully dried at lower temperatures. Small quantities of leaves can be dried in a forced air dehydrator, but larger quantities will need to be laid out on drying screens and/or racks. Leaves should be fully dry within a few days and should maintain their vibrant green color. Leaves that are dried too slowly tend to discolor and turn a pale yellowish-green.