What kind of trees are you planting, and what size?

Keep in mind that trees have surface roots you need to encourage and water too. And your goal is to get the tree to root deep AND wide, not just near the pipe.

That pipe works well for big palm trees, but it's a waste of time for almost everything else.

You would do better with some terracing between trees. You don't need anything elaborate, just a berm on the downhill side to retain water at the canopy line.

They do better with 100% native soil, with the "organics" applied as a mulch to retain water. If they have a cushy moist soil, the roots tend to stay in that area and they fall over in the first high wind.

*Dig hole just as deep as the tree root mass and about 2-3x as wide
*Fill hole with water and let it drain
*Repeat the water filling and draining (water UNDER the root mass to lure them down)
*Plant tree, backfilling with native dirt from the hole
*Water entire area of hole thoroughly, add dirt if it sinks.
*Mulch

When you water, apply water between where the rootball is and the edge of the hole. You want moist soil there to lure the roots.

Thanks for your reply.
i'm planting ficus nitida and podocarpus graciliors for hedging. The pipes were incorporated to stop/reduce runoff as i water the plants.
What i planned on doing was to have a soaker hose laid under the mulch for weekly watering and the pipes set in for summer intermitten watering, fertilizing in the spring and grey water irrigating.
typical summer temps reach about 108-113 during peak and i really want i nice healthy hedge.

I am sorry but I do not agree with lazygarden. We have the same set up as aptruncata on all 10 fruit trees along with a sting acadia and larger plants. This system was taught to us from a women who lived in Sedona all her life. It creats a very deep tape root and during the moonsoons/winds keeps them in the ground (no uprooting)and the trees/plants look for their own water down deep. They also grow very fast. I would recommend this system to everyone. We don't put a cap on top of ours just a flat rock, kinda looks like a mushroom, then if we want more water than the drip hose is providing we can stick the regular hose in the pipe. Also can add liq. fertilizer. About the cap on the bottom, ours are open don't know if a cap on the bottom will slow the water release.

thanks for you advice, i'm glad to know the setup works for some people. I've invested nearly $1200 in trees alone and wanted to have a bulletproof plan.

A tree's roots that absorb water and nutrients are located within the top 12 inches of the soil. You'll find the majority in the area of the drip line or edge of the canopy and many extend well beyond this point. Newly planted trees won't have this extensive root system of course, but within several months their roots will grow into the surrounding native soil as long as there is moisture available.

The deeper anchoring roots are more or less confined to the region near the trunk, and don't do much in the way of absorption.

By watering at the drip line (and moving the water source out as the tree grows) the region near the trunk will remain relatively dry and much more stable so trees won't blow over in high winds.

Here is a link that might be useful: New tree planting