Removing the dead or dying flowers from annuals and herbaceous perennials, as with roses, prolongs the plant’s flowering period.  The function of a flower is to attract pollinators that  will enable the plant to set seed.  As soon as they have produced seed most plants will stop expending energy on creating more flowers.  Taking off dead flowers before seed has formed encourages the plant to carry on producing more flowers.

Deadheading is one of gardening’s easier jobs – the sort of thing you can do during a stroll round the garden on a summer’s evening with a glass of chilled Chablis.  With plants that flower close to the stem, such as daylilies, Campanula and Coreopsis, you can simple pinch out the dead flowers between your finger and thumb.  Flowers that grow in panicles, or on the end of short stems, should be cut off individually.  Follow the stem of the dead flower down to where it joins a main stem, and cut it off.  I use lightweight snips with pointed blades, sold as florist’s snips, as these are easier to manoeuvre right down to the base of the stem you are removing.

Flowers that grow on long, single stems, such as Cirsium, Kniphofia and Delphiniums, should be cut down at the base of the stem.  Use your secateurs to get amongst the plant’s foliage and cut the stem off as close to the ground as possible.

Deadheading will, of course, prevent plants from seeding about, so if you want your aquilegias, for example, to sow themselves around the garden you will need to leave some flowers to set seed.  Seed is also a useful source of food for wildlife, particularly in the autumn, and seeing a family of chaffinches gorge on the seed of Echinaceas is a far more inspiring sight than that of a few extra flowers.

Occasionally a bud and a dead flower can appear remarkably similar.  The first time I was given my own dahlias to grow I carefully removed lots of buds thinking that they had already flowered.  In general buds are fat and firm.  On dahlias the buds tend to be rounded and hard while the flowered ‘shell’ is pointed and squashy.

Not all perennial plants will re-flower after deadheading or cutting-back, but removing the dead flowers and foliage will improve the plant’s appearance.  These include: iris, peonies, lilies, Actaea, Aruncus, Acanthus, Epimedium, Bergenia, Ligularia, Mellittis, Rodgersisa.