Since its inception in 1954, the NC7 Regional Ornamental Plant Trials have evaluated 623 different accessions of woody landscape plants under a wide range of environments across the North Central U.S. and at other locations with similar climatic conditions. The evaluation of replicated field plantings at multiple locations has a long tradition in forestry (Langlet, 1971; Wright, 1976) beginning with common-garden trials of tree populations in the 1700s and leading to the development of modern, replicated designs in Europe in the early 1900s. By evaluating many provenances of the same species at numerous sites, considerable knowledge has been accumulated about tree adaptation in relation to geographic origin and to climatic and edaphic conditions at the evaluation sites. This knowledge has been valuable in matching forest trees to appropriate production sites and has facilitated the breeding and selection of superior tree populations for timber and Christmas trees (Wright, 1976).