Container Planting of Douglas-Fir

Mechanized forest-tree planting in the Pacific Northwest dictates that machinery must be manually transported over the planting sites. This limits the weight and method of operation to that of growing seedlings in containers of specific dimensions. Accordingly, a rigid container was chosen that could be mass produced from a relatively inexpensive material. Polystyrene was selected to fill the needs of mass production by injection molding. The container was designed in the shape of a bullet. To permit root egress from the bullet to the surrounding soil after planting, the walls of the bullets were weakened by strategically located grooves, splits, and holes. The bullets are 2-1/2, 3-1/2, 4-1/2, and 5-1/2 inches in length, 7/8-inch in outside diameter at the top, and have walls 1/16-inch in thickness. The bullets are molded into strips of 12 or 18 and are placed directly in disposable plastic trays to form the basic unit of 216 bullets. Planting guns are used to plant all sizes of bullets without adjustment whether in strips or as single containers. Trays of seeded bullets are placed in wood troughs and sub-irrigated with water containing a damping-off fungicide and fertilizers. Seedlings are usually 1-year-old when planted.

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