Needless to say, greenery is what your garden is made for; not least because of the environment, but because planting is a form of decoration in the same way that hanging artwork on interior walls is.
Think not just of low-level plants, but in which areas you might like to add height, to draw the eye and to create a sense of intimacy, as window treatments do indoors. Could a climbing rose on a trellis close to your outdoor dining table add a romantic dimension to the setting? Or something delicately scented like honeysuckle or jasmine that fragrances your garden’s soft seating area in a way that no sofa-side vase of flowers in your sitting room could. For serious density, consider the English classic that is wisteria – the most curtain-like of all the climbers – that will also introduce a hearty dose of colour and texture to further your garden’s palette.