In the experiments described here, plants of Deutzia gracilis, Kerria japonica, Thuja plicata and Viburnum dentatum were grown in 10.2-litre containers in a mixture of pine-bark and peatmoss (85:15) in Michigan, US.
In the control treatment, 19mm of water was applied each time to each container (1.07 litres per container) via overhead sprinklers. Daily water use was measured with a soil-moisture sensor and run-off was recorded. The other treatments were: a) apply 100 per cent of the daily water-use; b) apply 100 per cent on one day and 75 per cent the next day; and c) apply 100 per cent on one day and 75 per cent on each of the next two days.
Applying water according to daily water use required at least 33 per cent less water than in the control treatment and plant growth was unaffected. Thus growers can conserve water, reduce run-off and reduce the loss of nitrate and phosphate to the surrounding ground by scheduling irrigation according to daily water-use.
Further savings might be made by grouping together for irrigation those plants that have a similar daily water use.
Container-grown Ornamental Plant Growth and Water Run-off Nutrient Content and Volume Under Four Irrigation Treatments by Warsaw, Fernandez, Cregg and Andresen (2009). HortScience 44 (6): 1573-1580. Members of ISHS can view HortScience from the website www.ishs.org.