I'm in Florida .. growing st augustine so that's my study knowledge.

With Air Temps in the lower 70's at night & if the grass blade stays wet about 8 hours before it sees some sun, is supposedly when the bad stuff starts growing or takes hold anyhow.

So watering after midnight would be fine here .. except we have watering restrictions / schedules that screw up that potential nicety.

Just make sure that the watering stops just about the time the sun comes up so that things have a chance to dry.

A lot of people have heard that. It must be from somebody's uncles brother inlaw.

How many golf courses water all night long?
How many large turf areas like business complexes water all night and part of the day?

Don't over water, but don't worry about what time.

Figure out what time you want the watering to be done, in most cases that is the first shower of the morning. Add up all the zone times and subract that from your finish time and you get your start time.

that is strange b/c the manual for our irrigation system specifically says to water at night, ending right befor the sun comes up...

I defer to Jerry Baker (The Impatient Gardener) about maintaining lawns. He says in his lawn book that the best time to water is between 7 a.m. and 11 a.m., but definately finish by 2 p.m. Otherwise, you help the spread of fungus and disease.

So if you have a 5-6 hour watering schedule, it should fit nicely between 7 a.m. and 2 p.m.!

BTW, the golf courses water at night because they can't afford to spray their customers. It's more economical for them to buy and apply lots of fungicide than to drive off patrons.

I'll go with the 7-11 hours, but not about deferring to Jerry Baker. I bought one of his products which was totally useless. Then I found out his advice served mainly to promote his huge family mail order company.