Biggs will start at the RHS in August following a 30-year career in the travel and leisure industries. HTA director-general David Gwyther said Biggs needed to help the charity lend "its considerable weight to policy issues when there is a need for it".
Biggs replaces Gordon Seabright, who has filled in as director-general since Inga Grimsey resigned last year. Seabright will retain his role as RHS commercial director.
Garden writer Peter Seabrook said Biggs should spend time working alongside staff to learn the ropes. "The new chief executive at Morrisons, I'm told, spent his first month working in every department. The RHS is now a big commercial operation and at a time of great change it would be reassuring for the staff to see their new director-general working alongside them," he added.