He is to be part of a 240-mile, six hour run, cycle and rowing challenge to raise money for Garden Re-Leaf on 14 March when the garden centre charity day is expected to feature a record number of participants in events at retailers nationwide.
Douglas-Davies' 240 mile journey will take him to each of his eight Hillview Group centres. The challenge will be based at Studley Garden Centre and will be completed on exercise equipment.
Representatives of suppliers including Hartman and Alexander Rose will also compete against each other.
Other highlights of the day include all The Garden Centre Group’s 139 centres holding events, including raffles, tombolas, wishing trees and having staff dress as gnomes.
Fresh@Burcot has a mural to add to, Ayletts is holding an indoor garden fete while Sunshine Garden Centre in London is one of the new participants.
Millbrook Garden Centre is offering a prize of David Domoney’s advice for a day and Klondyke is donating £1 for every cup of tea bought.
Alton Garden Centre director Andy Bunker said the event will "create interest and raise money for the cause".
Actors David Tennant and Naomi Harris are voicing a quiz that many centres are using.
The event has raised £116,000 for Greenfingers in two years.
For more details go to www.gardenreleaf.co.uk