It hopes that its 6,000 US members will help to raise £50,000 towards preserving a collection of rare horticultural literature held at the society's Lindley Library.
The Lindley Library is a priceless archive of books, periodicals and drawings dating back to the 16th century. The society wants to raise money to digitally record the contents of the library and believes a US audience will respond to an appeal that focuses on protecting horticultural heritage.
Direct marketing agency Whitewater has put together a campaign that includes a personal letter from the charity's president, Sir Richard Carew-Pole, and a carefully designed mail pack that draws on the society's history and Royal connections.
"Many people think because of our name we're a rich charity, when really we rely almost solely on the generosity of our members," said Lottie Cole, appeals manager at the Royal Horticultural Society. "Our US supporters are obviously committed to helping us from overseas, so we believe that they will react positively to an appeal that asks them to help conserve such a significant legacy."
Donors contributing $5,000 will be offered the opportunity to personally sponsor a rare book and have their name recorded by its entry in the digital catalogue.
"The fact that our US donors are supporting us shows that they like to be actively involved with our work, and hopefully this campaign will induce them to give a little more," said Cole.
The society is also using the Lindley Library appeal to assess the potential for targeting international donors in its Bicentenary Campaign, due to launch next year.