Chapter 6: Shade Structures for Ginseng
Ginseng is classified as a shade-loving herb. A lack of shade will result in leaf necrosis in a few days, and over an extended period time, total plant death. In its natural range east of the Mississippi River, ginseng will be found under the canopy of deciduous hardwoods (oak, maple, beech, hickory, birch, etc.) where the leaves of the trees shade the ginseng leaves and stems. For woods cultivated and wild simulated (see Chapter 7: Woods Cultivated ginseng) ginseng growers utilize the forest canopy to mimic the conditions where wild ginseng grows naturally.
Early in the 1900's the use of wood-lathe shade panels was common in ginseng gardens in Wisconsin and Ontario. The lathe was 1.5" wide, 3/8" thick, and 48" long. Lathe strips were stapled to 1 " by 3" by 14' long boards to form 4' by 14' panels. Wooden posts supported 2" by 4" rails, which in turn supported the shade panels. With the wood lath spaced 1.5" apart, the dappled light beneath the panels was felt to closely mimic the filtered light beneath a deciduous forest. To completely cover an acre of garden, no less than 900 panels were required! The panels had to be tied down to the top rails so that strong winds did not lift them away. Shade-lath panels were orientated so that the lathe strips ran in a north-south direction. This arrangement would allow an alternating dark/light pattern to fall upon the plants beneath, as the sun traversed across the sky.
Wood-lathe panels had to be taken down and stored during the winter as snow loads would damage them. The architecture of the gardens only allowed one full bed (4.5' wide) with 2 half width beds as posts were set every 12 feet. Factors that contributed to the demise of the wood-lathe gardens included the time and materials to build the panels, the need to take them off in the winter, their weight, and finally the introduction of modem plastic weave shade panels.
Essentially all of the major ginseng producing regions in North America have now adopted the use of the modern polypropylene woven shade panels. The industry has come to adopt the standard width of 24'. Other industry widths that are less common include 30' and 36'. Ginseng shade cloth has been engineered to screen out 78% of the incident overhead light, thus once again providing conditions mimicking the deciduous forest. Currently, the Premium Quality ginseng shade ordered from Pacific Rim Ginseng is selling for $.149 per square foot. Remember that there is 43,560 sq. feet in an acre. Shade panel weave has .75" to 1.5" wide dense strips, interwoven with more open weave, depending upon the shade cloth manufacturer. Shade panels can be ordered in any length, though the 168' length is about the limit that 2 workers can handle.
Figure 1 depicts the posts and shade panel arrangement for a one acre garden.
While ginseng shade panels can be ordered directly from the manufacturer, many growers use distributors located in the major ginseng production regions (Ontario, British Columbia, Wisconsin, and more recently the Pacific Northwest).
When shaping ginseng beds it is generally suggested that the rows run in a north-south direction. The alternating dark/light weave pattern will thus block the sun's rays as it traverses the sky from east to west. If the shade panels ran in an n east-west orientation the plants beneath would receive a continuos exposure to sun through the open portions of the weave. The only exception to the north-south orientation would be for sites with less than perfect drainage where rows should run up and down the slope. The shade structure is then designed to run the length of the beds. By having the ginseng garden longer than it is wide, fewer passes will be needed with the tractor over the life of the planting.
and erects the shade structure
Prior to setting up the shade structure, raised beds are formed with a bed plow (see Chapter 5: Planting the Garden). The trellis structure is generally erected during the August-mid October period prior to the fall rains. Care should be taken in setting up the series of posts and wire used to support the shade panels. The support system will need to be laid out in a perfect rectangle in order to provide a stable support for the panels over the 4 years the crop is being grown. Growers may choose to rent a transit in order to make sure the line and-cross are set up square.
There need to be an equal tension on all four sides of each panel so that there are no slack areas. Water damage to the ginseng plants below can occur in the spring after the shade panels have been stretched out. Rain water will tend to collect where the panels are loose. When the surface tension breaks, water will cascade onto the plants beneath either washing them away or can start an area of saturated soil leading to Phytophthora. root rot.
As seen in Figure 2, perimeter posts other than the 4 corner posts are situated on the inside of the line defining the layout of the garden. The four perimeter posts are to be centered on the intersecting lines defining the garden. Each of the four perimeter posts should receive 2 anchor cables and deadmen. Outside line posts are set every 24' the length of the garden. This will allow for a 24' bay through which the tractor will enter. On the interior of the planting, line posts are also set every 24'. On windy sites growers may elect to provide ground anchors from the line cable to the ground to prevent wind from pulling up posts. Cross-cable posts on the perimeter of the garden are set every 12" and are anchored.
Shade panels should not be pulled over the support wires in the spring until the ginseng plants started to emerge. By waiting as long as possible, the ginseng beds will have more time to dry out. On new gardens, attaching the shade panels for the first time is more challenging than in succeeding years. First lay a shade panel parallel with an outside line cable. Bunch the panel and lift it onto the cross cables. After all of the panel has been placed on top of the support system go back and secure on end at an outside perimeter cross cable with #2 hog rings. Walking the length of the garden reach up and secure the panel to the line cables, pulling the fabric and securing it with hog rings. Don't attach rings near posts until the panel has been pulled uniformly tight around its perimeter. Even after the panel has been pulled to the end of the garden, and secured along its length, the grommets on either side of the posts should not be attached with hog rings. With tension, the panels can be ripped near the posts if they are attached.
In the Northwest ginseng growers use either 8 or 10-foot pressure treated posts. Eight-foot lengths are more common as it is easier to reach up and handle the shade panels. Ten foot posts are suggested for locations that don't receive adequate air movement. The better air movement offered by the taller posts has to be weighed against the disadvantage of shorter workers needing a step ladder to reach the line and cross cables. Non-treated posts are available as well, though they generally only last one growing cycle. Steel posts are also available. Steel posts come with pre-drilled holes for cables to run through, and are galvanized for years of service.
Postholes can be dug with an auger digger mounted on the PTO of a tractor. Posts should be set approximately 1.5' into the ground. This will allow approximately 6.5' of headroom to work under beneath the shade panels. A disadvantage however, of using the pothole digger, is that on soft ground the posts can sink over time with the downward pressure exerted by the cable anchors. An alternative would be to use a pneumatic post pounder mounted once again on the PTO of a tractor (see Figure 3). Experience has shown that pounded posts don't sink under the load of the shade structure. Of course 10' posts can be substituted for the more common 8' posts. A 10' post will accommodate taller tractor heights. For a one-acre garden, 110 posts will be needed.
There are a number of different ways that posts can be anchored. There are screw augers that can be driven in using electric drills powered by portable generators. Other growers bury a 34' length of pressure treated post 2' deep and 6'-9' away from the upright post. The cables that run from the top of the line and cross posts serve 2 purposes. Not only do they lead to buried anchors, but they can also serve as support for side shade panels.
can lift up with wind
The weight of the shade panels and wires supporting them is only part of the reason to secure posts. The main reason for a secure anchor is to keep the shade panels from pulling the posts out of the ground when wind gets under the panels. Even though polypropylene shade cloth weave is quite porous there is still enough substance to catch the wind and potentially pullout the posts. As discussed previously, interior line cables can be anchored. Ginseng industry suppliers often sell screw anchors for this purpose.
Consideration should be given to the installation of shade panels (see Figure 4) situated along the length of the outside perimeter line cable. Without protection from the suns rays, the perimeter beds can suffer from sun exposure. Side curtain shade panels can be ordered in various widths, though 3', 5', and 6' wide panels are standard. Side shade panels offer 60% to 89% shading. Side shade panels are generally used on ends of the gardens where tractors enter. To reduce sun damage growers generally seed the ends of the gardens.
Northwest ginseng growers use either 1/8" wire rope or aircraft cable for both the line and cross cables. With the amount of tension needed to keep the shade panels tight, growers will need to take the time needed to properly install the cabling system. Nearly 7,000 feet of cable will be needed per acre of garden. Growers often work with a shade cloth supplier to procure cabling and the hardware that goes along with it. For gardens with wood posts, growers generally use 1 or 2 different methods to secure cables. In the first method growers will drill holes (3/4") near the top of the posts, through which cables can be fed through and secured with clamps (see Figures 5, and 6).
In the second approach the cables are run over the top of the posts and secured with 2" fence staples (see Figure 7). Separate anchor cables are used to keep tension on line and cross posts. A fence stretcher or come-a- long is used to pull cables tight.
In either approach, some growers put 2 cross cables on each post. In this manner the shade panels are sandwiched between the cables, once again to keep the panel more secure ( see Figure 8).
Besides the staples and cable clamps mentioned previously, growers will also need hog rings (#2) to secure the shade panels, which come with grommets, to the line and cross cables. Hog rings are crimped on special hog ring pliers. In the fall, when the top growth of the ginseng has died down, workers will cut the rings on only one side of the shade panels. The shade cloth panels are then pushed over to one side of each bay (24'-36' wide) where they are bundled and tied to secure them during the winter (see Figure 9). For staple removal growers use a modified crow bar ground down to fit under the staple.
Generally when growers buy their shade panels from a particular company, they also buy their hardware as well. There is no universally accepted technique for shade garden construction. Farmers' ingenuity plays a large role in shade support construction.
With the prolonged exposure to winter rains in the Pacific Northwest, all posts and anchor should be checked in the late winter prior to stretching out shade panels. Saturated ground can loosen the tension on the entire shade structure.