"why water at all?" the answer is simple, the plants need it. In an average summer, the water deficit in the southern part of the UK comes to around 300 -350 mm., this being the difference between average summer rain and what plants will generally consume through evapotranspiration. Unless that deficit is made up, planting suffers. New planting can die, or take years to become established and established planting will perform at well below its best, rather negating the benefits than should be expected from the investment in landscape. In the UK, it used to be acceptable for the landscape to go off in the summer as it always recovered in the autumn, but standards are generally rising and expectations of investors are perhaps not as flexible as they used to be. A properly watered landscape will not only develop quickly and look far better than an unwatered landscape, but, as it is growing constantly, regardless of summer deficits, it will take more wear and tear from those who use it and constantly recover from that wear and tear. For example, popular golf courses that have invested in full irrigation (fairways as well and greens and tees,) have found that they are able to vastly increase traffic through the course without detrimental effect with the investment recouped from increased fees in under two years.

So, Why Not Hand Water?

Well, first of all, there is the sheer quantity of water used. That average deficit above translates to around 750,000 gallon of water (or 3,500,000 litres) on a hectare of planting through the summer and that is not going to come through a half inch tap! Then there is the matter of judging demand and applying what is required and no more. How can that be done with hose pipes and portable sprinklers. Hand methods have no absolute control and hand watering tends to be in response to an obvious demand, fire-fighting the effects of a deficit rather than keeping everything in top-notch condition. As well as being uncontrolled, hand watering lacks uniformity of application and is therefore wasteful of water. An automatic watering system can achieve, and even better, 90% uniformity of application; with hand watering, only dedication will allow uniformity to approach 50%. Hand watering cost money. As well as the infrastructure costs for mains and taps throughout the landscape, it has a massive labour requirement. On a like-for-like basis, it can be demonstrated that automatic watering has a payback period of about eighteen months, or two seasons. Hand watering also interferes with the use and enjoyment of the landscape. It has to take place during the day (which can also bring in problems associated with plant damage through scorching,) and its infrastructure of hose pipes is annoying to those using the landscape, as is the fact that some part of the landscape will always be wet. Automatic watering gets over these problems and gives a better product in the end.