Voting slips were sent to the society's 200,000 members inside copies of the August issue of its journal, The Garden. The RHS council will make its final decision when the voting closes in mid-September.
Yesterday also saw the publication of a report by Sir Ralph Gibson examining the alternatives for the overcrowded library. He sets out three options without recommending any one: to keep the present dual operation split between London and Surrey; to offer just one library in London; or to move everything to Surrey.
The ballot on the alternatives will allow RHS members officially to register their fury at the council's proposed solution to the shortage of space at the Lindley library, the best horticultural library in the world, boasting about 50,000 books.
Presently split between the RHS headquarters at Vincent Square, south- west London, and its centre at Wisley, Surrey, the RHS council said in January that both libraries should be integrated at Wisley.
Its recommendation followed a report last November which concluded that the split library, which is together valued at pounds 10m, required duplication and did not satisfy users. "To maintain two major libraries within 25 miles of each other makes little sense," it said.
Hundreds of RHS members disagreed with the consultants' logic and bombarded the society with more than 500 letters to express their anger at the potential loss of the London base.
One letter from an influential group of gardening writers, including Sir Roy Strong, former director of the Victoria and Albert Museum, argued strongly that the library should remain. Users were overwhelmingly opposed to the move, they said. "Almost without exception every garden author or journalist (regardless of where they live) is agreed that the library should stay in London."
The writers emphasised the difficulty of reaching Wisley by public transport, particularly for foreigners who make up 10 per cent of the Lindley library's users, and the cost and shortage of overnight accommodation locally.
The president of the RHS, Sir Simon Hornby, admitted yesterday that the council had got it wrong, adding ruefully: "I became, rather unfairly, the villain of the piece."
The council has done a U-turn and is now supporting a compromise proposal - to keep both London and Surrey branches open but to apply for heritage lottery funding to help with the estimated pounds 6.6m cost of expanding both operations.
However, Sir Simon warned that the council had the constitutional right to override the findings of the ballot to find out which option members prefer. "If there is an overwhelming vote one way or another we would be mad not to follow it," he said. "But if the vote was narrowly divided we would reserve the right to the final decision."Reuse content