Optimizing phosphorus fertilization for two commonly grown ground covers: creeping jenny and periwinkle

Abstract

Growing nursery plants in containers usually requires the addition of fertilizer to achieve optimal growth. However, misconceptions among growers often lead them to apply quantities of fertilizers exceeding the recommended dose, resulting in nutrient runoff and increased production costs. Reducing fertilizer application is beneficial to have healthy plants and environment as well as to save on fertilizer costs. In this study, we wanted to determine the minimal level of phosphorus (P) required to grow bedding plants i.e. Lysimachia nummularia ‘creeping jenny’ (moneywort) and Vinca minor ‘Bowles’ (periwinkle) in nursery. The plants were grown within a greenhouse in a mixture of peat moss, vermiculite, and rice hulls (3:1:1 v/v) substrates and subjected to various P treatments. The treatments included single dose of 1, 3, or 6 mg/L of P, double doses of 3 or 6 mg/L of P, or a control that received 6 mg/L of P at each irrigation. The results indicated that single dose of 6 mg/L of P had similar fresh weight compared to control in both taxa. Reducing P application further to a single dose of 1 and 3 mg/L reduced fresh weight and leaf area in both groundcovers however did not reduce their stem length or physiological parameters such as Soil Plant Analysis Development (SPAD) and normalized difference vegetation index (NDVI). Phosphorus concentration in the plant tissue at maturity was lower in all treatments than control for both the taxa. During the study period, control plants received 26 times the dose of P compared to plants receiving 6 mg/L of P once. Therefore, this study outlines the possibility of reducing P fertilizer application while growing these groundcovers in nurseries for sale.