Each garden centre signing up to the fundraising effort will begin their Plant-athons at 4pm on Thursday 17 March and finish at 4pm on Friday 18 March.
Andy Bunker (Alton Garden Centre), Bob Hewitt (Klondyke), Alan Roper (Blue Diamond Group) and Greenfingers trustee Boyd Douglas-Davies (Hillview) will be using their own centres to showcase their fundraising efforts.
Andy McIndoe and the president of the Chartered Institute of Horticulture, Andrew Gill, will be joining Dennis Espley at Squire's - who will start and finishing their Plant-athons at the slightly earlier time of 2pm. Will Armitage has also pledged to take part in the 24hr Plant-athon at a garden centre in the North of England.
Hillview chief executive officer Boyd Douglas-Davies, founder of Garden Re-Leaf Day and a trustee of Greenfingers, said: "I’m really looking forward to taking part in the Plant-athon, which is already shaping up to be one of the fundraising highlights of the year - never before have we had so much support so early on in the campaign, but we need more.
"With the charity walk taking place for a second year, the quiz becoming more family orientated, and product promotions from Gardman and Briers, Greenfingers Garden Re-Leaf Day is already shaping up to be the best since we began in 2012."
Contact Greenfingers on 01494 674749 or email firstname.lastname@example.org.