Among them, the Royal Botanic Gardens, Edinburgh saw a 10 per cent increase to 889,420, adding to a 19 per cent rise in 2014. RBGE credited their Lights programme in the winter months for the increase.
The Eden Project saw an 11 per cent increase to 960,029 visitors, compared to a 1 per cent increase in 2014.
All four RHS gardens had record visitor numbers in 2015, with RHS Garden Hyde Hall in particular up 12.1 per cent to 242,520 visitors. Rosemoor visitor numbers were up by 9.5 per cent, Wisley by 6.1 per cent and Harlow Carr by 5 per cent.
Kew Gardens saw a more modest increase of 3.5 per cent, but Wakehurst Place, which Kew leases from the National Trust, saw visitor figures climb by 14.9 per cent - a strong turnaround from 2014 when the introduction of carparking fees saw a 29 per cent fall in visitor numbers.
Many National Trust properties held steady or saw more modest gains. Standouts include a 15.2 per cent increase in numbers at Bodnant Garden in Wales, 10.3 per cent at Lanhydrock and 17 per cent at Mount Stewart in Northern Ireland.
The UK as a whole saw a 3.2 per cent increase in visitor numbers, while Scottish attractions proved particularly popular, gaining 5.48 per cent overall.
Chester Zoo was the most visited paid-for attraction in England outside London, mainly as a result of the opening ‘Islands’ in June - a recreation of the tropical environments of six South East Asian islands.
The British Museum continued to be the most popular visitor attraction overall for the ninth year running. But visits to many London attractions plummeted following the Paris attacks in November.
Bernard Donoghue, Director of ALVA, commented: "2015 continued to be a record year mainly due to our members continuing to show how diverse the UK is to both domestic and overseas visitors."
He added: "The current weakness of the pound to the dollar and Euro is making the UK a more affordable destination and 2016 is on target to be another memorable year for ALVA members."