All plants need water and Best Feeds Garden Centers has some basic watering tips.

Improper watering is the number one cause of plant failure.

1. Water consistently  - Quality v Quantity Water regularly, consistency is essential. Water in the morning if possible so the plant can use water all day.  Second best time, early evening.

2. How Much - Depends on the plant.  Not a great answer but plant tags will help. Lawns and shrubs need about 1 inch per week.  But crowded gardens with plants competing for water will need more.  Soil also plays a role - clay soil will hold more, sandy soil not so much. 

3. New plantings - how to water new plants - New plantings should be watered at the base.  Plants drink through their roots so no need to spray leaves - sometimes that can be harmful.  Water at a slow pace, like it just rained and not a flood.  Water down 4-6 inches.   Shallow watering causes shallow roots.