Performance of Florida Landscape Plants When Irrigated by ET-Based Controllers and Time-Based Methods

Abstract

The combination of inefficient irrigation of residential and commercial landscapes and prolonged drought conditions has overextended the water supply in many areas of Florida. New irrigation technologies including smart irrigation controllers have been shown to decrease outdoor water use. The objective of this study was to evaluate the effects of evapotranspiration (ET) controlled and time-based irrigation treatments on the growth and quality of three ornamental plant species grown in landscape settings in Florida. Plumbago auriculata, Lagerstroemia ‘Natchez’, and Liriope muscari ‘Big Blue’ were established in mixed irrigation plots in a completely randomized block design with four irrigation treatments: 1) Weathermatic ET controller treatment; 2) Toro ET controller treatment 3) time-based treatment (determined by month from 60% of historical net irrigation requirement specific to South Florida) and; 4) reduced time-based treatment (irrigation depth in treatment 3 was reduced by 40%). Results for the entire study period showed that the use of ET controllers did not result in water savings over the reduced time treatment. There was no irrigation treatment effect on plant growth (growth index or height) of Plumbago auriculata, Lagerstroemia indica ‘Natchez’, or Liriope muscari ‘Big Blue’ over the course of the study. Similarly, plant density and quality were unaffected by irrigation treatment throughout the study. These results suggest that all irrigation treatments applied more water than was needed and that these species would perform acceptably with less irrigation than supplied by the lowest treatment in the study.