Optimizing container production of American fly honeysuckle (Lonicera canadensis), beaked filbert (Corylus cornuta), and maple leaf viburnum (Viburnum acerifolium)

American fly honeysuckle (Lonicera canadensis W. Bartram ex Marshall [Caprifoliaceae]), beaked filbert (Corylus cornuta Marshall [Betulaceae]), and maple leaf viburnum (Viburnum acerifolium L. [Caprifoliaceae]) are native shrubs useful for northeastern and north-central US landscapes with dry, shaded conditions. Objectives of this study were to evaluate the impact on growth in containers of 1) growth media amended with expanded shale at 3 rates; 2) 2 rates of controlled-release fertilizer; and 3) pruning of maple leaf viburnum. Expanded shale added to growth media composed of 4 parts pine bark, 2 parts peat moss, and 1 part sand did not improve growth for these species, and significantly larger plants of American fly honeysuckle were produced in the control media (lacking expanded shale) than in the amended media. Over a 2-y production cycle, the higher fertility rate of 2.5 g nitrogen (N)/pot produced American fly honeysuckle plants that were larger and had more shoots than did American fly honeysuckle plants that received 1.0 g N/pot. For beaked filbert, the higher fertility rate can produce greater growth, but may not do so every year. Fertility rate did not affect growth of maple leaf viburnum. Plants of maple leaf viburnum that were pruned after transplanting into trade #1 containers had visual quality ratings 2 times greater than unpruned plants. Pruned maple leaf viburnum had equivalent plant height and width and a more symmetrical and full appearance than did unpruned maple leaf viburnum plants.