Keep on deadheading
The simple act of removing faded blooms from plants will prolong their flowering season considerably. This is especially effective with the tender perennials that we use as container and patio plants, plants such as busy lizzie, fuchsia, pansy, pelargonium, petunia, and arctotis (pictured below). Some flowers, such as those of pelargonium (tender geranium) will snap off easily between thumb and forefinger, while others need a scissors, or little secateurs.
Some hardy perennials - lupin, antirrhinum (snapdragon) and delphinium - may give you a second flush if you remove the spent flower spikes, water the plants and give them a mulch of garden compost or well-rotted manure.
Prolific self-seeders, among them alchemilla (lady's mantle) and aquilegia (columbine) should be assiduously sheared of their old flower heads unless you want plenty more of the same. If you give alchemilla a severe haircut, leaves and all, it will produce fresh foliage, and probably another set of flowers.