Responses of Landscape Groundcovers to Minimum Irrigation

Abstract

Four irrigation regimes based on percentages of real-time reference evapotranspiration (ET 0 ) were applied to six widely used species of landscape groundcovers ( Baccharis pilularis ‘Twin Peaks’, Drosanthemum hispidum , Vinca major , Gazania rigens v. leucolaena ‘Yellow Cascade’, Potentilla tabernaemontanii , and Hedera helix ‘Needlepoint’) during a 17-month period in Irvine, CA. Irrigation treatments (50%, 40%, 30% and 20% of ET 0 ) were applied when accumulated real-time ET 0 × treatment percentage reached 4.0 cm (1.6 in). Although the response to irrigation treatment was species dependent, Baccharis , Drosanthemum , and Hedera maintained at least minimally acceptable visual quality with applied water equal to 20% ET 0 , while Vinca required a minimum of 30% ET 0 . Acceptable visual quality of Gazania and Potentilla were not maintained at any treatment. Visual quality of Potentilla was better at ET 0 greater than or equal to 30% ET 0 , but visual quality of Gazania was not improved with more water.