1. The water needs of plant materials.
* Once it is determined what the water needs of the plants are, the selection process for your plant materials comes a bit more easier. Some plant materials require regular ( 1-3 times per week ) watering to get the plants established to their new environments but, after the initial establishment period ( Sometimes between 1-2 weeks depending on the time of year when you plant and effects of possible planting shock ) the watering can be cut back a bit to help prevent root rot and disease. I have seen more plant loss due to "Over watering" than "Under watering" in my 25 years of landscaping professionally. Some plant materials such as Salvia Clevlandii do not like a lot of water at all during the warmer summer months and there are other plants that do not like a lot of supplemental water during certain times of the year. It is best you educate yourself on the watering requirements of the plants you want to install and be sure to "Group" them with other like watering plant materials.
2. Grouping the plant materials in suitable like water requirement hydrozones.
* Grouping the plant materials is just that. Planting like watering plants with other like watering plants. Using plant materials that normally receive at least 2-3 applications of water per week with plant materials that are better suited with 1 time per week would be a waste of money for you to purchase and install just because "It looks great". There are shrubs that during the summer months they receive hardly any water at all in their natural growing state. Observe what grows well together at your local botanical gardens or just take a road trip to the mountains or along the coast and observe what plant materials grow well together and fashion your landscape with the "Groupings concept" in mind.
3. Irrigating the plant material efficiently.
* All plants have water needs that are either Low, Medium, or High. By grouping like water requirement type landscape plants, this will help you reduce the chances of losing those plants by over watering or even under watering. With all the excitement of using drip irrigation and other water efficient means of applying the water such as rotating nozzles and water saving pop-up sprinkler heads, it is not a problem now-a-days to use cutting edge technology to save water and properly irrigate your plant materials. The judge is out in my humble opinion on wheter to use drip irrigation or overhead spray nozzles on native landscapes. I use both depending onthe plant materials and zone area I am watering. For large expanse of plantings where we have replaced the lawn for lower water use plant materials, we use rotator typoe nozzles to cover more square footage and give a more uniform application of water. For long runs of shrubs say in the parkway or planter bed, I use drip line with emitters or inline drip emitters depending on the plant materials and zone where we are planting. For turf areas and large ground cover areas, I have started using "Sub-surface" drip more as it is the most efficient use of watering there is out there in the field today.
By following the three tips above, you are on the right path to making sure you have the "Right Plant For The Right Place"