With the UK’s temperate climate, many people ask if it is worth irrigating. In this article we look at the benefits of irrigation.
Covered Areas and Restricted Root Zones
Where planting is under cover or experiences rain shadowing from tall buildings, irrigation is essential to keep the planting alive. If trees are planted in urban areas, with hard landscaping around the root area, irrigation will be needed to supply the trees water needs. Even medium sized trees require 100 litres per day in dry weather. Modern control systems can be programmed to take rainfall into account when scheduling outdoor irrigation zones while ignoring rainfall for covered or rain-shadowed
Speeding up Establishment
Where planting needs to mature quickly or is being used as screening, irrigation will greatly speed up the process. As the graph indicates, during the bulk of the UK growing season,
plants experience a Water Deficit. This graph is for an ‘average’ English year, for a ‘1-in-5’ dry year the deficit is even greater, as the rainfall levels are lower and the Evapo-transpiration (ET) levels are higher, widening the deficit between the two. As plants require water as part of their growth process unless this deficit is made up by irrigating, their growth will be reduced. As a rule of thumb irrigated landscape planting will establish approximately 50% faster than non-irrigated plants.
Reducing Plant Losses
As landscape contractors generally have to provide a warranty with the plants, costs due to plant failure can be expensive, especially if there is an unusually dry spell. The cost of integrating an irrigation system into the planting scheme is often quite small compared to the cost of the planting. In addition, the irrigation can often be sold to the client as part of a ‘value added’ package.