Hardwood Bark for Packaging of Bare Root Nursery Stock

For the past 3 years nurserymen have been utilizing peat to place an artificial ball around bare root nursery stock to extend the planting season and increase survival. Since hardwood bark was successful in the container growing or ornamental plants, hardwood bark was used to replace peat in this process. Four grades of bark were used: 1) A fine grade with 70 percent of the particles 1/8 inch or smaller; 2) a coarse grade with 60 percent of the particles 1/8 inch or larger; 3) ammoniated bark with 85 percent of the particles 1/8 inch or smaller, impregnated with 1.5 percent anhydrous ammonia by dry weight; and 4) composted bark with 85 percent of the particles 1/8 inch or smaller. Sedge peat which is commonly used in preparing an artificial ball, was used as a check. Bare root Spirea vanhouttei (Vanhoutte spirea) were balled in various grades of bark and peat and wrapped in burlap bags and burlap bags plus plastic bags, some of the plastic bags were unperforated, some were perforated with 1/4 inch holes, and some with 1/2 inch holes. Temperature and CO2 levels of the media were recorded. With the solid wrap, CO2 levels reached 8000 ppm, in the perforated wraps it ran only 3266 ppm. Temperatures in the bark media were slightly higher than the sedge peat but not enough higher to inhibit growth and were higher in the solid plastic wrap than the perforated wrap. Composted bark gave results almost equal to sedge peat for plant growth, and has an excellent potential as a packaging material.

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