. I have an idea to get a few lengths of black
drain pipe drill some holes down the side on the lower part, seal the
bottom
and sick them along side the larger plants in the soil in a upright
position. Them when the plant needs watering I fill the drainpipe and let
the water drain slowly out of the pipe, now I know the roots will get the
water okay but does anyone do this and if so does it work and more
importantly did you notice a saving in water use.

I have seen young trees with drainpipes next to them in the Geffrye Museum
gardens. http://www.geffrye-museum.org.uk/

Maybe you could speak to them to see how they work.

HTH

Natalie