I am still actively deadheading many plants in the hope of a more flowers from a long, warm, sunny Autumn – some hope editor
Plants look tidier if they are lightly trimmed when deadheading
Energy is put into the remaining plant rather than seed production. So plants may be better able to withstand winter and some will have a better established root system.
Softwood that has no time to ripen will probably suffer in the first frosts so it is pruned out
Dying flowerheads may rot or damage other flowers or leaves.
Deadheading stops unwanted seedlings from prolific seeders
Cons
If you want to save seed you want seedheads to ripen on the plant. Some will dry in a greenhouse or garden shed before being stored in an airtight container. I put seeds in small ex-mail order envelopes first.
Some seed heads such as Honesty, Rose rugarosa, Echinops and Teasels are left through winter for shape and to look attractive in a frost.
Do not deadhead ornamental plants grown for their seedheads like Iris Foettisima or Physalis
If you want to save seed or berries for birds and wild life do not deadhead
If you want self-sown seedlings for a natural garden then select what flowers to leave to run to seed.
