rockm

I would second, third and fourth BB's opinion. Watering systems CAN provide a false sense of security, not to mention they can also put off critical knowledge of your trees' care.

Watering isn't a scheduled thing, especially in summer. Water requirements can vary terrifically in spring and summer. You could not only wind up not providing enough water, but too much.

I wouldn't use an automatic system until you know what is required of each of your trees--this can take a number of years to acquire. Varies not only by species and season, but by time--trees that have not been repotted in some time can take some specialized watering as the soil mass gets more compact.

Wait on the auto watering system until you know how your trees work...