Garden visitor numbers have risen by up to 54 per cent this year compared to the wet 2012, with better weather and the Olympic and jubilee "displacement" helping to boost figures.
Kew was 54 per cent up from May to September, while nationwide garden visits rose by 30 per cent on average, according to the Association of Leading Visitor Attractions (ALVA).
Garden retail spend was up six per cent and catering up eight per cent. Garden visitor figures beat the 22 per cent rise of heritage and cathedral as well as museum and gallery figures nationwide.
RHS garden visitor numbers from the beginning of January to the end of August stand at 7,661,000, up by 425,000 on 2012. Wisley is up 15 per cent. RHS retail sales are 5.9 per cent up.
ALVA director Bernard Donoghue said: "Last year was dreadful so this year is looking particularly good for visitor numbers, mainly because of better weather.
"Many gardens looked at how to improve their year-round offer through pricing, events and new products because they didn't want to be caught out like they were last year."
He added that the weak pound against the euro is also an advantage, while London attractions have done particularly well after being "hit by the Olympic displacement of last year".
At Leeds Castle, managers declare whether it is a wet weather day by 9.30am each morning. If it is, then children can come for free.
West Dean in West Sussex attracted a record 22,500 to its annual chilli festival. A Grow, Cook Eat festival with Mary Berry last week was expected to bring in 7,500.
VisitBritain says £7.8bn was spent by tourists at gardens in the UK this year. It identified that of the 31 million people who visit Britain each year, around a third visit a park or garden, with around 2.4 million aged 25-34 and 1.4 million 55-64.
There were 2.1 million visits from those aged 35-44 involving parks or gardens, while nearly three-quarters of a million were over 65. Overall, those aged under 35 were particularly likely to visit a park or garden, with 41 per cent of visits compared with 33 per cent of visits from those aged over 35.
The latest figures confirm that going to a park or garden is one of the most popular activities for overseas tourists, accounting for 36 per cent of all visitors, placing only behind eating out, going to pubs and shopping
July to September accounts for four million of the annual tally. By contrast, just 1.6 million visited gardens in the first quarter of 2011.
The French make up the largest market, with 1.25 million visits, spending £406m. Visitors from America are second, with 1.23 million visits, spending £1.1bn.
Alan Sargent, garden consultant
"Last year there were far too many events, with the jubilee and Olympics. People got events fatigue, with everything from garden visitor numbers to our local harvest supper down because everyone had run out of money. This year there's a feel-good factor and people are loosening their wallets. Numbers are up 10-15 per cent. Autumn festivals will make numbers even higher."