Waltham Abbey Gardens in Essex, Gostry Meadow in Farnham and Phillips Memorial in Godalming, Waverley, achieved gold at South East in Bloom, along with Gunpowder Park in Essex which also scooped Best In Category.
Success came too in the South West, where Weston-super-Mare and Portishead in Bloom both took gold, with Torquay and Tavistock in Bloom achieving silver gilt at South West in Bloom.
Elsewhere, Babbacombe Downs, Friends of Tessier Gardens and Worle Village achieved outstanding in the pennant awards.
The core objective of Britain in Bloom is to recognise horticultural achievement, environmental responsibility and community participation.
To win gold, the highest of five standards, entries must score 85 per cent or 170 points out of a possible 200.
Mike Brunskill, sales and marketing director at Glendale, said: "The in Bloom awards acknowledge the importance of both sustainable environments and sustainable communities, both of which are key priorities of the work Glendale undertakes.
"These wins reflect what Glendale is about; maintaining the highest level of service delivery, through the hard work of a team of specialists, dedicated to making a real difference to the environment while bringing communities together."
Weston-super-Mare is also in the national Britain in Bloom finals which will be announced at a ceremony in Sunderland in October.
Glendale and its horticulture arm Glendale Horticulture supported the 2015 South West in Bloom campaign as an official sponsor.