How much drip irrigation should mature avocado trees get (in gallons per hour)?

First, we need to specifically identify which of the three varieties of Avocado trees you have. There are three types of Avocado trees: Mexican, Guatemalan and West Indian. The Mexican tree is more suited for cold climates and produces smaller fruit with thin skins, while the Guatemalan trees produce fruits with hard bumpy skins. West Indian trees are better suited for warmer climates and produce fruits with shiny skins.

There is an organization whom you might wish to contact, known as the California Avocado Commission. Their website is here:

http://www.avocado.org/

I’m certain that they, being the experts on proper Avocado propagation, can answer any and all questions you may have, to your complete satisfaction.

Good luck with your growing!