On 03/06/2014 22:32, Roger Tonkin wrote:
I have an automatic watering system for the greenhouse. It is
fairly basic and allows me to water once or twice a day at two
different times.

Last year I watered for an hour in the evening (7.00pm), this
year I'm doing half an hour am (6.00am) and half an hour in the
evening (6.00pm).

What do others do? Which is best?

There is some advantage to some morning watering and some evening as
well. The plants have more chance to absorb it at night.

OTOH a few things that are prone to rot dislike being wet overnight.

Be sure to tune your automatic watering regime well ahead of a two week
holiday or you will come back to some very wet pots.

--
Regards,
Martin Brown