Growth and physiology of deciduous shade trees and conifers in response to fertilizer and media in pot-in-pot production systems for northern climates

Container production is increasing relative to balled-and-burlapped (B&B) production throughout the US. Pot-in-pot (PIP) production is a form of container production that combines the benefits of conventional above-ground container production with those of field production. The goal of this research was to develop guidelines for fertilizer application and media type to improve PIP production for growers in the upper Midwest. The project consisted of two studies: (1) examining fertilizer effects on seven taxa of deciduous shade tree, and (2) examining effects of fertilizer and media on four conifer species. Growth and physiological responses were measured throughout two growing seasons. From the first study, we found that fertilizer addition increased growth of shade trees largely by increasing total leaf area per tree. Suggested fertilizer rates are consistent with previous recommendations of adding 6.33 g·L -1 container. Increased leaf area resulted in increased water use and reduced stomatal conductance, which likely offset any increased photosynthetic efficiency due to fertilization. Results from the second study indicate that maximum growth of conifers occurs with fertilizer addition between 3.92 and 7.84 g ·L-1 container. Furthermore, for container substrates consisting of pine bark and peat moss, a single mix of 80% bark to 20% peat moss is appropriate for all the species tested.