The week-long event is due to take place in the Royal Gardens of Highgrove House, near Tetbury, from 11 April.
TV gardeners Alan Titchmarsh and Rachel de Thame and chef Raymond Blanc will be among the guest speakers at the event. Tony Kirkham, Chris Beardshaw, Bob Flowerdew, Carol Klein, Jekka McVicar, David Domoney, Sarah Raven, head gardener Debs Goodenough, Bunny Guinness and Andy Sturgeon will also speak at talks/demonstrations/suppers which cost £25-£200 each.
Charles and Camilla are not expected to attend but the festival.
Highgrove House was acquired by The Duchy of Cornwall from the MP Maurice Macmillan in 1980.
All profits will be donated to the Prince of Wales's Charitable Foundation.
Charles held a week-long garden festival at his London residence Clarence House in 2010. Some 70,000 were expected at Garden Party to Make a Difference at Clarence House but the 12-day event attracted just 30,000 visitors.