Evaluation of ornamental plant performance on four deficit irrigation levels: working with industry to promote sustainable plant choices for summer-dry regions
Since 2005, a series of 2-year plant trials have been performed on perennial plants to assess their performance on four levels of deficit irrigation based on real-time reference evapotranspiration (ET0). Initial trials were performed on plants on the UC Davis Arboretum All-Stars list, plants already in the trade recommended for their hardiness, good looks, and low water use. These trials have expanded to include new grower introductions for sun and shade. The following Arboretum All-Stars species or cultivars were planted in fall 2009 for evaluation: Aster 'Purple dome', Bulbine frutescens 'Tiny Tangerine', Rosa 'Korbin', Helleborus 'Red Lady', Heuchera maxima, Osmanthus heterophyllus 'Purpureus', Ribes viburnifolium, Woodwardia fimbriata. These nine new introductions from Ball Ornamentals were also evaluated: Abelia ×grandiflora 'Sunshine Daydream', Buddleia 'Podaras #8' ('Blue Heaven'), Cordyline 'Purple Sensation', Escallonia ×exoniensis 'Fradesii' ('Jamie'), Hypericum androsaemum 'Red Ignite', Ligustrum sinense 'Sunshine', Lomandra confertifolia ssp. rubiginosa 'Seascape', Mimulus 'Curious Georgie Boy', Trachelospermum jasminoides 'Sebra'. After 18 months of establishment irrigation at 80 to 100% of ET0, plants were given one of four levels of deficit irrigation during the following irrigated growing season at 20, 40, 60 or 80% of ET0. Monthly plant measurements and quality ratings were taken to assess plant performance, and from these data a recommended irrigation rate or range was made for each plant. These recommendations are being used by a wide range of landscape professionals making decisions about plant choices and maintenance irrigation levels for water-conserving urban landscapes.
Reid, K. and Oki, L.R. (2016). Evaluation of ornamental plant performance on four deficit irrigation levels: working with industry to promote sustainable plant choices for summer-dry regions. Acta Hortic. 1112, 155-162
perennial plant trials, irrigation trials, low-water landscapes, drought-tolerant, water conservation, ET0-based irrigation