Contractors and supervisors, landscaping, grounds maintenance and horticulture services supervise and coordinate the activities of workers in the following unit groups: Nursery and greenhouse workers (85103) and Landscaping and grounds maintenance labourers (85191). They are employed by landscaping companies, cemeteries, lawn care and tree service companies, nurseries and greenhouses and by landscaping operations of public works departments and private establishments. Contractors may be self-employed.