More than 1,000 entries to this year's show were whittled down to 73, shortlisted by regional RHS judges to go through to the national UK finals.
Volunteers have become bulwarks, with more than two-thirds of entries now led by volunteers or volunteer-council partnerships.
"A lot of people have tried to associate what's happening in local authorities with a downturn in Bloom participation," said RHS community horticulture manager Stephanie Eynon. "That's not what we have seen."
The number of entries in Bloom, billed as "the nation's largest environmental campaign", was at a similar level to previous years.
Although some authorities pulled out of the competition - Liverpool announced last month that it had quit (HW, 20 January) - more were "harnessing the power of volunteers", said Eynon.
Meanwhile, around 35 new entrants replaced those dropping out. These included the villages of Bray in Berkshire, Cartmel in Cumbria and the town of Linlithgow in Scotland.
Finalists came from as far as Guernsey and Jersey, Wales, Ulster and Northumberland as well as villages and industrial heartlands.