On the surface, watering lawns can seem like a very easy and straight forward task, put the sprinkler on the lawn, turn of the tap, and switch it off after a while. Unfortunately this is a very wrong assumption. There are only a few simple rules to watering and the difference between following them and not following them can be huge when it comes to areas of lawn health, water bills and the health of the environment.
By properly understanding how and when lawns use water we can then see and understand how to water lawns correctly for the ultimate benefit to achieve the best lawn health.
Lawns can only absorb water when it's vascular system is active, and this only happens through photosynthesis, which in turn only occurs when the sun is out. So lawns can only absorb water during the daylight.
For this specific reason, the best time to water a lawn is in the morning. This gives the lawn an adequate supply of water throughout the day, and through the power of photosynthesis, the lawn will uptake as much water as it needs, and which is then readily available.
Watering lawns at night results in no immediate water being absorbed by the lawn, and much of the excess water then runs through the soil profile and down into the water table. Using this method, much more water will need to be applied to the lawn in order that enough water is still left in the soil profile when the morning arrives and the lawn can begin absorbing water again. Big savings on water bills can be achieved through daylight watering.
The trouble of watering lawns at night which results in more water being drained into the water table can also cause environmental damage. If a lawn receives excess amounts of fertiliser, these nutrients can also be washed into the water table causing excessive pollutants to enter the water supply.
The final issue which arises from night watering of lawns is lawn disease. Most lawn disease are fungal by nature. They thrive and spread most easily in dark moist environments. Watering at night creates a perfect breeding and spreading environment for most lawn diseases, so any infestation of lawn disease will in fact be much worse than they may otherwise be if lawns were watered in the mornings.