Growth and Quality Response of Woody Shrubs to Nitrogen Fertilization Rates during Landscape Establishment in Florida

• Published in: HortTechnology (Alexandria, Va.) Va.), 2013-12, Vol.23 (6), p.898-904
• Main Authors: Shober, Amy L., Moore, Kimberly A., West, Nancy G., Wiese, Christine, Hasing, Gitta, Denny, Geoffrey, Knox, Gary W.
• Format: Article
• Language: English
• ISSN: 1063-0198; 1943-7714
• DOI: 10.21273/HORTTECH.23.6.898

Despite inconsistent reports of nitrogen (N) fertilization response on growth of landscape-grown woody ornamentals, broad N fertilization recommendations exist in the literature. The objective of this research was to evaluate the growth and quality response of three landscape-grown woody shrub species to N fertilizer. Three ornamental shrub species, ‘Alba’ indian hawthorn ( Raphiolepis indica ), sweet viburnum ( Viburnum odoratissimum ), and ‘RADrazz’ (Knock Out™) rose ( Rosa ) were transplanted into field soils in central Florida (U.S. Department of Agriculture hardiness zone 9a). Controlled-release N fertilizer was applied at an annual N rate of 0, 2, 4, 6, and 12 lb/1000 ft 2 for 100 weeks. Plant size index measurements, SPAD readings (a measure of greenness), and visual quality ratings were completed every month through 52 weeks after planting (WAP) and then every 3 months through 100 WAP. Plant tissue total Kjeldahl N (TKN) concentrations and shoot biomass were measured at 100 WAP. Results of regression analysis indicated little to no plant response (size index, biomass, SPAD) to N fertilizer rate. Shrub quality was acceptable for all species through 76 WAP regardless of the N fertilization rate. However, quality of rose and sweet viburnum fertilized with N at the low rates (