In the evening,at dusk or later, so that the water has a chance to sink in and get to the roots without evaporating in the heat of the day. In the South of France the gardeners set the irrigation system to come on at about 1:30 am so that the ground is wet through to the right depth before sunrise.It is a mist system, so that it acts like a very light rain. I don't suppose, in the absence of a timed sprinkling system, you'd want to follow their example. On the other hand it might intrigue the locals if you were out there with a hosepipe in the early hours. Or you could have a 'bring a bucket of water' party on the lawn, I suppose, at midnight?
Even though getting out of bed at 1:30 to drag around a muddy hose sounds like a good time I think I'll pass and water in the late evening. Thanks fred, it's been so hot and dry here that even though I water everyday our lawn still has some dry spots, so maybe the later watering time will work better.
Thanks fred, it's been so hot and dry here that even though I water everyday our lawn still has some dry spots, so maybe the later watering time will work better. 
