Garden visitor numbers shot up in 2013 for most garden attractions compared to the previous year, thanks to better weather and a lack of competing attractions such as the 2012 Olympic Games.
Latest Association of Leading Visitor Attractions (ALVA) figures show Kew was up 29 per cent and the National Trust's Sissinghurst was up 26 per cent.
But Eden Project numbers fell 9.9 per cent, Royal Botanic Garden (RBG) Edinburgh was down five per cent and many gardens have not recovered to 2011 levels.
ALVA director Bernard Donoghue said: "I'm delighted gardens did so well thanks mainly to the weather but also to the continuing appeal of RHS properties, botanic gardens and gardens of historic houses. This is encouraging in the lead-up to the 300th anniversary of Capability Brown's birth."
He added that good marketing, year-round events and better use of social media such as Twitter and Facebook to promote what is happening in the gardens on a daily basis, often through photographs, have helped numbers to improve.
National Trust visitor experience director Tony Berry said: "The weather had a positive impact on visitor numbers in 2013, especially with the warm weather over the summer.
"Also, last year more of our properties did more for visitors in the traditional 'shoulder' months of spring and autumn, building towards our aim of having a year-round offering for visitors."
He added: "In 2014 we will be aiming to build on these figures by continuing to extend our opening hours and encouraging visitors to experience seasonal highlights, which will include doing more with Christmas."
RHS art and media director Dan Wolfe said: "We are pleased with the 2.3 per cent increase in visitor numbers to RHS gardens in 2013.
"Visitor numbers at the UK's other outdoor attractions fell more sharply in 2012 and the eight per cent growth they have now seen in 2013 represents a recovery from that dip.
"Visitor numbers at the RHS fell less in 2012 as our gardens are not as reliant on summer tourism, so we had less ground to recover. We are delighted to see the wider industry recovering from the bad weather in 2012 and look forward to a great 2014."
Kew marketing head Tina Houlton added: "We are thrilled with the 29.4 per cent uplift. When the long-overdue summer finally arrived, our 'IncrEdibles' festival was well received by visitors, with the opportunity to take a boat out on the Palm House lake a particular draw on sunny days."
She said Kew's after-hours light spectacle and nature trail "highlighted that Kew is a garden for all seasons". But Wakehurst Place visitor numbers fell (see p5). An Eden Project representative said its fall in numbers was due to a continuation of the downturn of 2012 caused by poor weather, the recession and the Olympics.
"However, during peak season we were on par with 2012 and this stronger performance continued into 2014. Eden remains well ahead of the original projection before full opening of between 650,000 and 750,000 visitors per annum."
The ALVA's 53 members manage 2,000 tourist sites, which attract 100 million visitors - about a quarter of visits made annually in the UK.
English Heritage said "unprecedented" summer visitor numbers helped lead to overall increases.
RBG Edinburgh enterprise director Heather Jackson said a cold snap during March and April 2013 hit numbers, but its regional garden figures are up thanks to strong events.