Sweet pea Greenfingers has an old-fashioned scented cream grandiflora flower form.
Mr Fothergill's Tim Jeffries has pledged 25p to Greenfingers for every packet of 20 seeds priced at £2.45 the Suffolk seedsman sells through its retailers, mail order catalogue and website during the 2016/17 gardening season.
He said: "We are delighted to support such a worthwhile charity and a cause close to so many hearts. By launching sweet pea Greenfingers, we hope we can raise the charity's profile with our customers, Britain's gardeners and the garden trade."
Head of fundraising at Greenfingers Linda Petrons officially named sweet pea Greenfingers at Mr Fothergill's annual trial grounds open day for the gardening media in mid August. She said: "We would like to say a huge 'thank you' to Mr Fothergill's for this thoughtful gesture, which we hope will not only make more people aware of the work we do, but will also raise vital funds to help us continue creating magical and inspiring gardens for children who spend time in hospices right across the UK."