Greenhouse production of Impatiens wallerana using a controlled-release fertiliser produces quality finished plants with enhanced garden performance

Abstract

SummaryThe use of controlled-release fertiliser (CRF) has been identified as a best-management practice because CRFs supply localised nutrients to the surrounding substrate over a period of time, and so can reduce the amount of nutrient that is leached from the pot. However, no information is available regarding the application of CRF during plant production, and how that can affect the subsequent garden performance of a crop. The objective of this research was to evaluate the effect of CRF, applied at the time of plug planting, on the finished quality and garden performance (post-production) of impatiens (Impatiens wallerana Hook. f. ‘Xtreme Scarlet’) plants. Plants were fertilised with a water-soluble 20:4.4:16.6 (w/w/w) N:P:K fertiliser (WSF), applied at each irrigation event at a rate of 150 mg l–1 N, or with a 16:3.9:10 (w/w/w) N:P:K CRF with either of two longevities (5 – 6 or 8 – 9 months) at a rate of 6.8 kg m–3. Impatiens plants were grown in a greenhouse and transplanted to the field, where no fertiliser was applied. Shoot dry weights (DW), flower numbers, leaf greenness, and consumer ratings were determined for plants grown over two successive Summers in Columbus, Ohio, USA. In Experiment I, plants grown with CRF had similar DWs to those grown with WSF during the greenhouse phase; however, in Experiment II, plants grown with CRF during the greenhouse phase had at least 52% more flowers than WSF-grown plants.At the end of the field phase, CRF-treated plants were less chlorotic, had 33 – 45% higher shoot DWs, produced 25% more flowers, and had 82% higher consumer ratings than plants grown with WSF. Growers can therefore use CRF to produce a high-quality impatiens crop, and can promote the use of CRF as a value-added practice that benefits consumers through enhanced garden performance.