As a pay-back for their time, Sunset usually took them all out to dinner. "There was a lot of time to talk to people afterward. Some of the biggest deals in landscaping were struck over those dinners," Williamson said.
Another editor who made major contributions to the book was John R. (Dick) Dunmire. He put together the 278-page Western Plant Encyclopedia, which first appeared in the 1967 edition.
It took Dunmire four years to compile, relying on a reference work called "Hortus II" for botanical names and on gardeners in the field who checked his facts and added input on how plants grew in different climate zones.
Before the Computer Age, Dunmire wrote each entry out in longhand and then copied it on a precursor to the Xerox called a Bruning machine.
"It was a machine that looked something like a gigantic toaster. It made copies, but it was clumsier and slower than the old mimeograph," he recalled.
For the 1978 edition, illustrations were added to the plant encyclopedia, a change that brought about the hiring of several artists.
In the last edition, published in 1988, a 24-page color section was added to kick off the book and an index to the botanical and common names of plants was compiled.
Each time the book comes out it is updated to reflect the latest information on gardening, said Elizabeth Hogan, Sunset's current book editor.
Sometimes, even the most basic information can be improved upon. Recently, the section on how to dig a hole was revised. "Instead of digging a very deep hole, now the theory is you should dig wide, shallow holes. We used to recommend digging a hole two or three times as deep as the plant root mass. Now, it's not believed to be necessary. Also, we now use natural soil to fill in the hole. Before, we used to tell people to use soil amendments," Dunmire said.
Over the years, the popularity of the Sunset Western Garden Book has not waned.
It sells about 75,000 copies annually, almost exclusively in the West. The book's editors get around 500 comments and questions each year from readers.
"It's still unique because it's comprehensive. Other pretenders have come along over the years but they don't last," said Clark.
Some have criticized the book for being slanted toward Northern California because Sunset's headquarters are located in Menlo Park. Other criticism has been that there is not enough illustration, that it does not get specific enough on exotic plants and that the climate zones could be more precise.
In the last two years, many of the original editors and writers of the book have retired, including Williamson, Dunmire and Clark. They were offered a severance package when Time-Warner bought Sunset Magazine and its book division from the family of L. W. Lane Sr. in June, 1990.
Will the book retain its charm and its old-fashioned, cultured writing style?
Never fear, said Clark. "Sunset still has tremendous interest in and knowledge of gardening. I can't see them ever dropping this book."
Western gardeners will always need a specialized book that deals with the opportunities and challenges of gardening in a climate that allows the growing of plants from tropicals to cacti, said Dunmire.
"Rudyard Kipling said that the British empire had dominion over palm and pine. Well, we've got that right here in California," he said.