On 10/06/2013 22:51, Roger Tonkin wrote:

I've bought an automatic water control from Aldi for
about £20. Works well, with lots of options, which is
the problem.

I am using it to water tomato plants growing in the
greenhouse in grobags, plus a few lettuces in the soil
there. Using small pipe drip feed system.

I have an option of 15, 30 or 60 mins once or twice a
day. How long and how often is appropriate? At the
moment I'm trying twice a day for 30 mins, which
looked to be about right during last weeks heat.
Trouble is I'm going away soon so I'll not have much
time to try other settings, hence the request for
advice.

Somewhere in between 15 and 30 minutes twice a day is probably about
right. Twice a day uses less water and has the advantage of morning and
evening watering which means the plants get a decent drink overnight.
This helps avoid trouble if it is very dry and sunny.

Things probably won't die if they get underwatered but might if they get
totally saturated. OTOH I can't see tomatoes or lettuces being too fussy
about overwatering. You can grow tomatoes with their roots sat in a
bucket of water as in ring culture - they need feeding too.

If the worst happens and you flood something out then just drain it off
when you get back. Most plants can stand being under water for a while
as a natural response to flash floods.

Other concern is that there was no advice on battery
life, so I'm a little concerned that the batteries may
fail whilst I'm away for 3 weeks. Being Aldi supplied,
only contact was a German web site!

If it is like my Hoselock model then about a year but keep an eye on it
as it will surely fail just when you need it most!

The easy way is to run the setup for the same length of time as you
intend to be away and watch what happens.


--
Regards,
Martin Brown