Usually you don’t have to worry about watering your shrubs unless:
They were just planted this year, or
They are growing in bare soil with no organic mulch, or
There is currently a serious drought in which there has been little rain for several weeks.
In any of these cases, you need to be thinking about getting some water to your shrubs especially during the heat of the summer months.
Our favorite device for watering shrubs is the porous soaker hose. For info on products and details about how to use a soaker hose go to the Tool Shed. Also check out more watering details at Watering The Landscape.