We report six confirmed cases of Legionnaires' disease in Scotland caused by Legionella longbeachae serogroup 1, identified over a four-week period in August–September 2013. All cases required admission to hospital intensive care facilities. All cases were amateur gardeners with frequent exposure to horticultural growing media throughout their incubation period. L. longbeachae was identified in five samples of growing media linked to five cases. Product tracing did not identify a common product or manufacturer.