A study was conducted to evaluate the growth of Ilex × attenuata Ashe ‘Savannah’, Lagerstroemia indica × fauriei ‘Natchez’, and Magnolia × Soulangiana Soul.-Bod. grown in a conventional above-ground container production system in #7 containers compared to an in-ground “pot-in-pot” (PIP) production system. Container production system had little or no effect on the shoot growth of the species used in this study after seven months. For the container phase of the study, root dry weight and total root dry weight increased for Lagerstroemia and Magnolia grown in the PIP system and the root: shoot ratio of Lagerstroemia increased 87%. Between 4 to 5 PM EST (July 1, 1991), root-zone temperatures in the western quadrant of plants in the PIP system were 13°C (23°F) cooler than aboveground containers in the conventional production system. Root ratings were higher for all three species in the PIP system. After being transplanted in the field for several months, few differences in landscape establishment between production systems could be seen for Ilex and Lagerstroemia. Results of these studies indicate that for Lagerstroemia, production advantages seen during the container-phase of the PIP system may not be evident after one season in the field.
Technical assistance of Bruce Tucker, donation of plant material by Wight Nurseries, and the statistical assistance of Ben Mullinix is gratefully acknowledged.