Postestablishment landscape performance of Florida native and exotic shrubs under irrigated and nonirrigated conditions.
Although new and innovative measures to reduce landscape water consumption are being sought, traditional methods of water restrictions and plant selection prevail. Species native to North America are often promoted as drought tolerant with little information to support or refute such claims. Furthermore, species performance is unknown in maintained environments such as commercial and residential landscapes. Thus, 10 native and 10 exotic species, commonly used in landscapes, were evaluated independently for postestablishment growth and aesthetics under irrigated and nonirrigated landscape conditions. Growth indices were recorded monthly, with dieback and plant density evaluated at termination of the experiment. At termination of the experiment, canopy size of eight native [beautyberry (Callicarpa americana), fringe tree (Chionanthus virginicus), yaupon holly (Ilex vomitoria 'Nana'), virginia sweetspire (Itea virginica), wax myrtle (Myrica cerifera), chickasaw plum (Prunus angustifolia), saw palmetto (Serenoa repens), and coontie (Zamia floridana)] and eight exotic [golden dewdrop (Duranta erecta), cape jasmine (Gardenia augusta), crape myrtle (Lagerstroemia indica), oleander (Nerium oleander), japanese pittosporum (Pittosporum tobira), indian hawthorn (Rhaphiolepis indica), sweet viburnum (Viburnum odoratissimum), and sandankwa viburnum (V. suspensum)] species were similar for irrigated and nonirrigated treatments. Irrigation resulted in larger canopy sizes for two native [walter's viburnum (V. obovatum) and inkberry (I. glabra)] and two nonnative [japanese privet (Ligustrum japonicum) and fringe flower (Loropetalum chinensis)] species. Among the native species with larger canopy sizes under irrigated conditions, all are indigenous to swamps and streams. With the exception of virginia sweetspire, plant density and dieback were similar for irrigated and nonirrigated plants of all taxa examined. Irrigated virginia sweetspire plants had higher plant density and dieback ratings than nonirrigated plants. Results indicate that, aesthetically, irrigated and nonirrigated plants were similar. Data emphasize the importance of selecting plant material adapted to existing environmental landscape conditions.