The firm, which has until now been one company looking after seven green activities, will be re-organised into five autonomous companies from 1 August.
Former managing director of Glendale Managed Services, Nick Temple-Heald, has been appointed to the board of Glendale's holding company, Parkwood, and he will become chief executive of the Glendale Division.
Temple-Heald said: "It has just got too big for one person to look after. This is not an exercise in saving money and it is not about throwing out employees - it is actually going to cost us money. We need the infrastructure for control in the business to allow us to embrace our next period of growth."
He added that when he arrived at the firm in 2004 its turnover was £28m, but that had risen to £54m by last year.
Glendale anticipates further growth following the acquisition of Silvanus Services and Landscapes Southwest in November.
Temple-Heald added: "The activity that has grown the most is Glendale Countryside, which has doubled in size with the acquisition of Silvanus. That was the final trigger (for these changes)."
He said Glendale's joint venture company with the TEG Group, called Verdia Horticulture, is set to open its first recycling facility at Hill Barton, Exeter, this autumn.
The five specialist companies are:
- Glendale Grounds Management - Managing director: Michelle Maybury
- Glendale Countryside - Managing director: Graeme Sibley
- Glendale Horticulture - Managing director: Richard Burton
- Glendale Golf - Managing director: Neil Simpson
- Glendale Recycling - Managing director: Nick Temple-Heald.