Think of your garden as a theatrical production. It's all right - you don't need any artistic training. You are aiming for a variety show that lasts a long time, offers year-round interest and alleviates boredom. The way to achieve this is to use a wide range of plants: from trees and shrubs to climbers, perennials, annuals and bulbs. What's the difference between them, and what can each of them bring to your garden?