Sage's promotion follows head of horticulture and gardening Caroline Linger's departure for Crocus. Linger will not be directly replaced.
David Mitchell is the next most senior plant buyer in Sage's team.
Category manager Mairi Devlin is also believed to have been promoted.
In June 2016, the group completed sale and leaseback of five freehold sites, raising £40.1m. Overall margin decreased from 56.5 to 54 per cent. Transaction numbers rose from 13.09 million to 13.23 million, with footfall conversion falling from 28.7 to 28.6 per cent. Average transaction grew from £18.95 to £19.28.