On 04/06/2014 17:49, Judith in England wrote:
On Wed, 04 Jun 2014 15:27:10 +0100, David Hill
wrote:

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?


I presume it is linked to some form of drip/trickle irrigation system.
I'd have thought that the thing you really want to know isn't how long
to leave it on for but how much water each plant is getting.
If you have individual pipes to each plant/pot then put one into a
bucket and see how much water you get in half an hour.
The problem with this sort of system comes when you grow a range of
plants with different requirements.


Not really, as you adjust the individual drippers accordingly.

But the OP did say he had a "fairly basic"