Medicinal Herb Crops - Root Herbs in Forest Farming

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 o 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 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.)