Gardens require water, but should they be irrigated? Four irrigation policies can be distinguished:
One school of thought believes in intensive irrigation. Computer-controlled irrigation systems are installed, with timing devices, pop-up sprinklers, humiditity meters etc. Irrigation can insure that lawns are always emerald and that garden plants never suffer from low moisture levels. The consequence of artificial irrigation is, of course, an artificial appearance.
The opposing school of thought spurns the use of artificial irrigation. The natural regime is for some plants to flourish in a dry season and others to flourish in a wet season. The city of Tucson in Arizona is a case in point: the municipal parks department formerly used intensive irrigation and grew plants which were not native to the habit. Since this resulted in high expenditure and a lack of local distinctiveness, the policy was changed. Desert plants were used instead, especially cactus species. In time, people became proud of their non-irrigated fauna and flora.
Artificial irrigation can be used 'as little as possible' to prevent desiccation..
The fourth policy is to collect and manage rainfall. The traditional method was to collect water in tanks and barrels. Gardeners have long recognised this as 'better' than tapwater: it contains more nutrients and less chlorine and tends to be warmer than mains water.
The modern approach, known as SUDS (Sustainable Urban Drainage Systems) is to manage all the surface water within the property boundary and adopt a policy of 'zero runoff'. All water runoff from paths, lawns and roofs is collected , stored and distributed using tanks, ponds, pipes and swales. The underlying principles are known to water engineers as detention, infiltration and evapo-transpiration. Paving should be porous. If all city dwellers adopt such policies
than urban rivers can be reclaimed from their concrete ditches and pipes. It is an exceedingly attractive policy. Water runoff is controlled at source (hence the term 'source control') instead of being discharged into drains and rivers.
Water vapour, from jets, keeps vegetation lush
Irrigation can create beautiful effects (at Sceaux). Irrigation < design involves both technical and aesthetic considerations. sprayed water is noless beautiful when it is irrigating plants.
Garden sprinklers waste water, but can be fun for kids