and for shrubs and other small trees you can just plant 2 or 3 litre pop
bottles with a few holes in the bottom with just their necks sticking out
this is another good way to get the water down deep and to encourage the
roots to grow Down, then they are more resistant to dry weather.
If you are sinking pipes then fill the top with wire mesh or something to
stop mice etc from falling in and being trapped.

--
David Hill
Abacus Nurseries
www.abacus-nurseries.co.uk