While most of the ginseng crop in North America is grown under artificial shade, it can also be produced in natural shade under hardwood trees (see Temperate Agroforester, January 1997). Growing consumer demand for ginseng and other medicinal herbs has created an opportunity for private owners of deciduous forestland, nut orchards or fast-growing tree plantations to produce a lucrative cash crop from the land prior to tree harvest. Besides ginseng, there are other shade-dependent medicinal herbs for which markets are expanding.

Herb Crops

Although many different understory plants can be grown in a forested environment for "special forest products," this article will focus o­n some of the perennials native to eastern and central North America whose roots or rhizomes are harvested and sold for their reputed medicinal properties. These plants include black cohosh (Cimicifuga racemosa), blue cohosh (Caulophyllum sp.), bloodroot (Sanguinaria canadensis), may-apple (Podophyllum peltatum), false unicorn root (Chamaelirium luteum) and, perhaps best known, goldenseal (Hydrastis canadensis).

Table 1. Selected Medicinal Root Crops Suitable for Forest Farming

* Per Oregon's Wild Harvest

At present, most of the supply of these plants is "wild-crafted" or collected from the wild. Due to increasing demand and high prices, some indigenous populations are being impacted by over-harvesting. American ginseng (Panax quinquefolius), goldenseal and other herbs are listed as "At Risk" by the group United Plant Savers, and several states officially ban their harvest. However, all are adaptable to cultivation in forest farming enterprises.

Marketing

Like any crop, markets for medicinal herbs are subject to the laws of supply and demand, and can be particularly volatile. Long before planting, forest farmers should thoroughly investigate which plants, among those adaptable to the microclimate and soils of their site, are most likely to be profitably grown. Establishing contacts with potential buyers before planting is essential to success.

Wholesale buyers for forest-grown fresh or dried herbs may be found among commercial growers or processors. Several national trade organizations for the herbal business publish directories of buyers and processors (see information sources below).

Oregon's Wild Harvest (OWH) is an example of a company which not o­nly buys, grows and collects herbs, but also adds value by processing them for both retail and wholesale markets. o­n their farm located near Portland, Oregon, OWH currently grows about 60 plant species. They buy both domestic and imported herbs, and collect other plants from native populations in the Northwest. Their o­n-site processing plant packages over 130 botanical and medicinal herbs for sale under their own brand and for several supermarket chains.

Organically Grown

OWH is certified by Oregon Tilth (a third-party organic certifier) as both an organic grower and processor. According to OWH President, Randy Buresh, demand for organically grown medicinal herbs is increasing as more supermarkets begin to carry organic produce. "While the general public doesn't fully understand the difference between certified organic and conventionally-grown herbs," he said, "more people are becoming concerned about the potential concentration of applied chemicals in the roots of plants which are used for medicinal purposes."

Since buyers like OWH will often pay more for organically-grown herbs than for conventionally-grown, forest farmers may want to explore organic certification for the portion of their land used for herb production. For example, the wholesale price for certified organic goldenseal is currently $70 per pound (dried) versus o­nly $40 per pound for conventionally grown or wildcrafted.

While national standards for organic production are being developed, growers and processors currently rely o­n either independent certifiers (e.g., Oregon Tilth, California Certified Organic Farmers, etc.) or, in some states, public agencies. Certification generally requires a three year transition period after last use of prohibited materials o­n or near the land to be used for organic production. Interested forest farmers can obtain more information about organic standards and the costs and procedures for certification from the private and public certifiers in their state.

Root Herbs in Forest Farming

The start-up costs of growing shade-dependent herbs under a tree canopy can be significantly less than under artificial shade. According to Jessica Cortell, OWH's farm manager, the per acre cost of establishing goldenseal under artificial shade cloth is about $17,000 compared to o­nly $5,500 under natural shade. However, potential disadvantages are that woods-cultivation may require more expensive hand labor and produce a lower yield compared to intensive, high-density cultivation under shade cloth.

For forest farming enterprises in new tree plantations, plant the trees at relatively wide spacing, e.g. 12 x 12 feet for hybrid poplar or 10 x 30 feet for black walnut. Early weed control is important not o­nly for the long term tree crop but also to hasten canopy closure, thereby creating the right level of shade for understory crops. Herbicides and cultivation can be used for the first 1-3 years, or until canopy closure is attained and weed competition is reduced by shading.

If the decision is made to grow herbs organically, it will be necessary to wait at least three years after the last use of herbicides before planting. Herbs crops such as goldenseal that can be harvested in as little as 3-4 years after plantings could fit into the last 3-4 years of a 10 year rotation of hybrid poplar. When canopy closure is attained in black walnut or pecan orchards, and alley cropping with food or forage crops therefore becomes less profitable, more shade tolerant herb crops could be introduced. Nevertheless, the presence of a perennial crop may limit other tree management activities, e.g. pruning.

For forest farming in native forest, stands may need thinning to allow growing space and control the percentage of shade. Select a site with good air and soil drainage in an area shaded by tall hardwoods. According to Jessica Cortell, shade dependent herbs can be cultivated under most deciduous trees, e.g. alder, maple, oak etc. However, she contends that production under coniferous forest cover is more difficult because shade levels are too dense, the soil is too acidic, and conifer needles may be toxic to some plants. If the decision is made to grow organically, the same transition period is necessary o­n that portion of the forest where medicinal crops will be grown.

Cultivation Practices

Since the herbs included above in Table 1 all have fairly similar growing characteristics, cultivation practices for goldenseal will be used as an example. Continuous cropping of ginseng is not advisable because of disease problems, and goldenseal or the other herbs are well suited as rotation crops for ginseng. Jessica Cortell of OWH provided the following summary.

Goldenseal grows best in moist, well drained soil, and summer irrigation may be needed in drier areas. Cultivation in raised beds between the trees in recommended for better drainage. In a forest setting, the beds could be shorter than in plantations or orchards planted o­n a grid. Raised beds should be limited to every other row in plantations so as not to hinder access. For goldenseal, beds 2-6 inches high and 3-5 feet wide are created with a bed shaper.

Goldenseal plants need 75-80% shade for best growth. Planting can be started from either seed, rhizome pieces or root cuttings. Although more expensive initially, planting 2 year old rhizomes or roots will produce a crop in o­nly 3-4 years compared to 5-6 years from seed. Weed control is important since goldenseal is not competitive with grass. Under organic production, weed control relies upon mulch and hand or mechanical cultivation. Fungal diseases such as botrytis and fusarium, and attack by slugs and snails are the main insect and disease problems likely to be encountered. When ready for harvest, roots are dug in the autumn after the tops have died. They are typically dug by hand, although a mechanical potato digger could be modified for this purpose.

After harvest, the roots must be washed and carefully dried. Unless the buyer is able to accept fresh roots, which are perishable, then growers would need to construct a forced/heated-air dryer. Drying reduces moisture content in goldenseal roots from about 70% to 10-15% in 5-7 days. Dried roots are easier to store and sell, and sanitation is important to prevent bacterial or fungal infestation. Buyers usually advise independent growers about drying and storage requirements. OWH routinely tests herb crops for E. coli and other pathogens. The price which buyers will pay for dried herbs varies with market demand for the different species, but is usually at 50% of the retail price per pound.

Before commencing a forest farming enterprise with medicinal herbs, tree growers should discuss their plans with potential buyers and carefully research the markets and growing requirements for different species. An abundance of printed and electronic information from herbal business trade organizations is available to help growers in this pursuit, a few of which are listed below.

Information Sources

• American Botanical Council, PO Box 144345, Austin, TX 78714, www.herbalgram.org
• Herb Growing & Marketing Network, PO Box 245, Silver Spring, PA 17575, www.hgmn.com
• Herb Research Foundation, 1007 Pearl St #200, Boulder, CO 80302, www.herbs.org
• International Herb Association, 910 Charles St., Fredericksburg, VA 22401, www.iherb.org
• Organic Trade Association, P.O. Box 547, Greenfield, MA. 01302, www.ota.com (Info about organic certifiers, growers, manufacturers, etc.)

This article originally appeared in the April 2000 issue of the Temperate Agroforester. Thanks to Randy Buresh and Jessica Cortell of Oregon's Wild Harvest (43464 SE Phelps Rd., Sandy, OR 97055) for their contributions to this article.