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).
Goldenseal is considered to be one of the most at-risk medicinal plants in the United States and is estimated to be at a high risk of extinction throughout its native range (Oliver, 2017). Goldenseal is typically found growing in densely clustered patches (Burkhart and Jacobson, 2006) on forested slopes, along stream banks, and in rich open woodlands from southern Ontario to north Georgia (Sievers, 1949; McGraw et al, 2003). For forest farmers, goldenseal is well suited as a stand-alone crop or as a companion plant within a mixed-species production system. Goldenseal has a high natural resistance to fungal pathogens and may help to reduce disease outbreaks when planted as part of a mixed-species polyculture. For example, it is common for ginseng growers to interplant goldenseal as a natural defense against the spread of fungal pathogens.
Goldenseal has traditionally been harvested for the medicinal properties of its rhizome (Foster, 1991) with the first documented use by European settlers recorded in 1769 (Persons and Davis, 2005). Traditionally, goldenseal has been used to treat a variety of applications, including as a strengthening tonic, stomachic, sore throat gargle, eye wash, and topical treatment for cuts, sores, ulcerations, and infections (Van der Voort, 2003; Pengelly et al., 2012). Noted declines in the abundance of wild populations, largely due to habitat loss and overharvesting, resulted in goldenseal being listed on Appendix II of the Convention on the International Trade of Endangered Species (CITES) in 1997. As a CITES regulated species, the U.S. Fish and Wildlife Service monitors all exports of goldenseal from the United States in an attempt to ensure that the harvest and trade of the species is sustainable (Robbins, 2000). In response to continued population declines, conservation advocates have suggested that a moratorium on the harvest and sale of wild goldenseal should be implemented to help protect the viability of remaining populations. Similarly, industry stakeholders have initiated efforts to research and develop sustainable harvesting, management, and cultivation guidelines that will help ensure the long-term survival of the species.
Goldenseal’s life cycle can be separated into three distinct stages of development: the seedling stage, the juvenile stage, and the reproductive stage. Following seed germination, plants can remain in the seedling stage of development for 1 to 2 years depending on the quality of the growing site. Seedlings do not develop a true leaf during the first year of growth, but instead persist with two small, round leaf-like cotyledons that may be easily overlooked. After 2 to 3 years of growth, plants reach the juvenile stage of development, which is marked by the development of a single palmately-lobed leaf (Burkhart and Jacobson, 2006). Plants will generally persist in the juvenile phase for 1 to 2 years before becoming fully mature. After 4 to 6 years of growth, plants will finally become sexually reproductive and will develop a forked stem with two leaves and a small white flower. The showy, white flower blooms almost immediately after the plant emerges and begins to unfurl its leaves in April. Like many woodland herbs, goldenseal flowers are pollinated by small bees and syrphid flies but are also capable of self-fertilization (Chafin, 2007). The fruit, a raspberry-like drupe, matures through the summer months, turning from green to red before ripening in mid- to late July (Van der Voort et al., 2003). The seeds, which resemble shiny-black BB’s, can exhibit single or double dormancy, with most seeds germinating the first spring if stratification requirements are met (Persons and Davis, 2005; Albrecht and McCarthy, 2011).
Although goldenseal can reproduce via seed production, most natural population growth occurs through clonal propagation (Van der Voort et al., 2003; Burkhart and Jacobson 2006) where adventitious buds form along the fibrous roots and eventually swell to emerge as a new plant (Albrecht and McCarthy, 2006). Clonal growth can result in large, dense populations with up to 100 stems documented growing within a 3’ x 3’ plot (Gagnon, 1999).
Goldenseal is primarily pollinated by small “sweat” bees of the genera Dialictus and Evylaeus, as well as syrphid flies and some larger bee species (Sinclair and Catling, 2000). Goldenseal is also capable of self-fertilization when conditions for pollination are unfavorable (e.g. cold, rain, etc.) or when cross-pollination is unsuccessful (Chafin, 2007).
The quick disappearance of ripe berries, their red color, and their position on top of the plant’s leaves indicates that birds may be the fruits’ primary consumers and dispersers (Eichenberger and Parker, 1976), but this has not been fully investigated to date. In addition to birds, a wide variety of animals and insects have been observed consuming goldenseal fruits and/or seeds, including wild turkey, mice (Philhower-Gillen, 2015), deer, chipmunks, squirrels, ants, raccoons, and possum.
Seed Collection and Stratification
Starting goldenseal plantings from seed is considered a less consistent method of propagation (Follet and Douglas, 2005), but you can increase the chances of success by following a few key guidelines. For best results, collect seeds as they ripen in July/August, and sow them as soon as possible. By sowing immediately after collection, the seeds are naturally exposed to the warm late-summer temperatures that are required to break seed dormancy and enable them to germinate the following spring (Albrecht and McCarthy, 2011). Research suggests that if seeds do not experience these late-summer temperatures, they are more likely to exhibit an extended dormancy, and germination will be delayed until the following year (Albrecht and McCarthy, 2007).
If desired, goldenseal seeds can be collected and stratified under controlled conditions and then stored for planting the following year. To prepare seeds for stratification, loosen the seed from the pulp by mashing the berries, and then soak them in water until the pulp begins to separate from the seed (Burkhart and Jacobson, 2006). After 24 hours, drain off the water and pulp fragments, while retaining the seeds. Rinse the seeds with a moderate pressure hose or faucet and rub them with your fingers to remove any remaining pulp (Albrecht and McCarthy, 2007). Once cleaned, the seeds can be stored in a refrigerator or buried in a stratification box for 2-3 months where they will be exposed to the warm/cold temperature fluctuations required to break seed dormancy. Research suggests that seeds should not be kept in stratification for more than 90 days, or delayed germination can result (Albrecht and McCarthy, 2007).
Propagation from Seeds:
After collecting or stratifying, simply plant seeds ½”-¾” deep in a prepared nursery bed or shallow planting furrow and re-cover with soil and 1”-2” of leaf litter. Seeds can also be planted using the wild-simulated technique previously described in Chapter 1, where seeds are broadcast on the surface of the soil (5-7 seeds/sq. ft.) and then covered with leaf litter. If seedlings have been propagated in a nursery bed, they should be transplanted to a permanent location after two years growth (Cech, 2002).
Propagation from Rhizome Cuttings:
Goldenseal is most commonly propagated by subdividing mature rhizomes into smaller rootlets that can then be replanted. Mature rhizomes should be divided into ½”-1” inch long pieces, as illustrated in figure 5. Each cutting should have healthy fibrous roots and a dormant bud if possible (Greenfield and Davis, 2004). Rhizomes and fibrous roots typically have several dormant buds, some of which may be imperceptible to the naked eye. If a rootlet has no visible bud, it is possible that one may develop after the rootlet is planted.
Propagation from Fibrous Root Cuttings:
In addition to whole rhizome cuttings, goldenseal can also be propagated by using portions of the fibrous root system. This propagation method mimics goldenseal’s natural ability to repropagate from root fragments that are severed during the harvesting process (Burkhart and Jacobson, 2006). The fibrous roots, which tend to grow prominently along the entire length of the rhizome, are covered with small dormant bud scales that, if given enough time, can develop into a new plant and root system. To propagate new rootlets from fibrous root material, simply cut the roots into ½”- 1” pieces, and plant them ½”- 1” deep in a prepared nursery bed. Given the small size of the propagule and the lack of well-developed buds, it may take up to two years for plants to fully emerge.
Goldenseal is typically found growing on north, northeast, and east facing aspects under a mature forest canopy that provides approximately 60%-80% shade (Davis and Persons, 2014). At higher elevations (< 3,400 ft.) growers have reported that goldenseal can tolerate as little as 45% shade and still maintain satisfactory growth. Within these baseline conditions, goldenseal prefers sites with well-drained soils that are rich in organic matter yet maintain a slightly acidic soil pH (5.5.–6.5) (Greenfield and Davis, 2004). As previously discussed, the presence of certain companion plants and other indicator species can also be used to identify suitable growing sites. Species that are commonly found growing in association with goldenseal include, but are not limited to, tulip poplar, sugar maple, basswood, black walnut, red oak, slippery elm, white ash (Burkhart and Jacobson, 2006), trillium, black cohosh, ginseng, mayapple, and bloodroot (Persons and Davis, 2005).
Site Preparation and Planting Using Wild-simulated Method
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. 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.
Planting Wild-Simulated Seeds and Rhizomes:
Whether you are starting with seeds or rootlets, goldenseal is best planted during the late summer and fall seasons. To plant seeds using the wild-simulated method, simply rake back the leaf litter on the forest floor to expose a 4’-5’ wide strip of bare topsoil, and then scuff the soil with a hard steel rake to slightly loosen the top ¼” of material. Once the planting bed is prepared, broadcast seeds at a rate of 5-7 seeds/sq. ft. until the bed is fully planted and then re-cover with leaf litter. After the leaf litter has been redistributed across the bed and the seeds are sufficiently covered, walk across the planted area to help improve seed to soil contact. Seeds can also be planted ½”- ¾” deep in a shallow planting furrow if the rake and scatter method does not meet your needs.
To plant rootlets, start by raking the leaf litter off of the planting site to expose a 4’-5’ wide strip of soil. Once the planting strip has been exposed use a mattocks or sturdy garden hoe to dig a planting furrow or holes for individual rootlets. Regardless of which approach you decide to use, furrows and/or holes should be dug approximately 2”-2.5” deep to ensure that there is an adequate amount of soil to sufficiently cover the rootlet and terminal bud. After the hole/furrow has been prepared, plant rootlets 2” deep with the fibrous roots spread laterally and the terminal bud approximately ½”- ¾” below the surface of the soil. Once the rootlets have been properly positioned, backfill the hole/furrow with soil and firm around the rootlet, and then re-cover the planted area with 1”-2” of leaf litter.
If seeds or rootlets are leftover at the end of the season, plant them as soon as possible the following spring (March – April) to ensure the best chances of survival.
Site Preparation and Planting Using the Woods-Cultivated Method
As we have previously discussed, woods-cultivated production systems are more intensively managed and will typically require more extensive site preparations. As previously described in the wild-simulated section, remove fallen branches and other debris that will interfere with the planting process. Since the woods-cultivated method relies on the development of tilled and cultivated planting beds to optimize growth, more intensive removal and management of existing vegetation will be required. In order to prevent unnecessary damage to surrounding vegetation, mark the boundaries of your planting beds prior to removing any trees, shrubs, or other vegetation from the site. Beds can be of any size and dimension but should be narrow enough to allow for easy maintenance and management (approx. 4’- 5’ wide). Once the beds have been marked, remove, thin, or prune competitive and suppressive vegetation within the planting area to help facilitate bed development, increase airflow, and optimize light conditions. After the vegetation has been removed, apply any necessary soil amendments, such as pelletized gypsum, sand, rock phosphate, or composted leaf mulch, and then shallowly till the beds with a heavy-duty tiller or tractor to loosen the top 3”- 6” of soil.
Planting Woods-Cultivated Seeds and Rhizomes
Once the planting beds have been prepared, use a hoe or similar tool to make shallow planting holes approximately 2”- 3” deep throughout the beds. The holes should be spaced 6”- 8” within rows, and rows should be spaced 8”- 10” apart. Wider row spacing (e.g. 12”) may be needed for longer cropping cycles. After the holes have been established, plant rootlets approximately 2” deep with the bud ½” below the surface of the soil. After the bed has been planted, recover the with 1”-2” leaf mulch.
In woods-cultivated production, seeds are typically sown in a prepared nursery bed, and then the seedlings are transplanted to a permanent location after 1-2 years of growth.
Maintaining the habitat conditions that you have either selected or created is an important part of any forest farming operation. The amount of maintenance required will vary based on the production methods used, the extent of site modifications prior to planting (e.g. vegetation removal, tilling, etc.), the occurrence and frequency of disease, and similar production variables.
One of the primary advantages of wild-simulated plantings is that they are relatively self-sufficient and typically require less upkeep and maintenance than their woods-cultivated counterparts. Common maintenance activities for wild-simulated plantings include, but are not limited to, regularly inspecting plantings for signs of disease, predation, and mortality; pruning and/or repruning competitive vegetation to maintain airflow and optimal light conditions; and periodically trapping/baiting rodents and other pests when crop damage is observed. In addition to the previously described activities, woods-cultivated plantings will likely require annual weeding to prevent the establishment and/or reestablishment of competitive vegetation within the tilled beds. Moles and voles also like to forage in loosely tilled soils and may require regular trapping/baiting to prevent crop damage.
Pests and Disease
Goldenseal is considered to be a relatively hardy and disease resistant species but is still susceptible to a variety of pests and pathogens, including botrytis leaf blight, fusarium wilt, root rot disease, and root knot nematodes as well as slugs, moles, and voles (Greenfield and Davis, 2004). The first line of defense in disease prevention is to select and maintain the habitat conditions that support healthy plantings. One of the primary factors that contribute to the development and spread of fungal pathogens is planting density; thus, as the density of your plantings increase, so does the potential for disease. Keep in mind that density can refer to the conditions within a single bed, as well as the conditions between beds. By developing dispersed plantings rather than large consolidated beds, the spread of pathogens between plantings (Burkhart and Jacobson, 2006) and the potential for large-scale crop damage can be reduced.
Goldenseal roots are harvested in the fall of the year as the plants begin to enter winter dormancy. If possible, wait until late September/October when the leaves begin to turn yellow and die back for the season. As the leaves begin to fade, medicinally active constituents are transferred to the root system, which increases the medicinal quality of the final product (Douglas et al., 2010; Burkhart and Zuiderveen, 2019). Aside from medicinal quality, there are other benefits to delaying harvests until the fall. Research examining the relationship between the timing of harvest and population recovery has shown that fall harvested populations recover faster than those harvested during the summer months (Sanders and McGraw, 2005; Albrecht and McCarthy, 2006). Growers have also reported that fall harvested roots have a better fresh to dry ratio, which can reduce the time required to fully dry the roots.
As a forest farmer it may not always be feasible to delay harvesting until plants begin to make this transition, especially if large quantities of roots need to be harvested and processed in a short amount of time, or when you need to adhere to the timeline of a specific customer. If harvesting cannot be delayed, at a minimum, plants should not be harvested until the seeds have been collected or dispersed, and the reproductive cycle has been completed.
Depending on the quality of the growing site, plants that were propagated from rhizome cuttings or rootlets typically reach harvestable size after 3 to 4 years of growth (Burkhart and Jacobson, 2006), and plants that were propagated from seed typically reach harvestable size after 5 to 7 years of growth (Greenfield and Davis, 2004). Keep in mind that these age ranges may vary based on growing site quality and other environmental factors.
All root material should be adequately washed to ensure that it is free from dirt and debris. Excess dirt remaining on the roots can contribute to elevated levels of bacteria, and can decrease the value of the final product. To wash small and medium-sized batches of material, briefly soak the roots in a tub of water to soften and loosen any foreign debris. Then spread the roots on a wire mesh screen and spray with a medium pressure hose to rinse clean. Some roots may need to be broken into smaller pieces in order to dislodge all dirt, rocks, roots, and other debris. The same technique can be used to wash large quantities of material, but it may be more efficient and cost-effective to use a commercial root washer or similar device. Whether soaking the roots in water or washing them with a hose, make sure the contact with water is as brief as possible to prevent the loss of desired alkaloids, specifically berberine and hydrastine. Alkaloid leaching from prolonged washing will not only decrease the quality of the roots but can also negatively affect the value of your final product. A simple way to monitor this is to observe the color of the wash water. If the water is turning yellow, then alkaloids, specifically berberine, are being leached from the roots.
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 forced airflow (e.g. fan) where temperatures can be maintained at 85-95∘F. In humid locations temperatures as high as 130∘F 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. Maintaining adequate airflow will help to eliminate moisture on the surface of the root and prevent the onset of mold development facilitating a faster, more even drying process. During the drying process, roots will lose approximately 70% of their weight depending on the original moisture content, and the color will darken slightly, turning from yellow to light brown. While the exterior of the root will darken, the inside of the root should maintain a bright and vibrant yellow color. 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.
Follow all recommended guidelines described in the GAPC section.