An idea that began simply as a way to bring together collectors of John Deere tractors to swap stories has blossomed into a full-blown convention that now draws more than 2,000 enthusiasts to the Quad-Cities.

The seventh Gathering of the Green will be March 14-17 at the Davenport RiverCenter. The event, organized by an all-volunteer committee, is held every other year and is dedicated to the John Deere antique two-cylinder and New Generation tractor restorers, collectors and enthusiasts.

“This year we’re celebrating 100 years of John Deere companies,” said co-chair and co-founder Ken Reese of McHenry, Ill.

According to Reese, Deere began to purchase other implement-related companies in the early 1900s, including the company that manufactured the Waterloo Boy tractor. “Deere purchased about 13 lines around 1912 ... to become a full-line company,” he said, adding that this year’s conference focuses on “the new John Deere company from 1911-1912 through 2012.”

The gathering comes as the Moline-based Deere & Co. celebrates its 175th anniversary.

Reese said the 2012 conference’s theme is “Generations of Power.” To illustrate the theme, the four sponsoring John Deere antique tractor clubs will be creating life-size replicas of five John Deere dealerships — spanning the 100-year time frame. They will depict dealerships from 1912, 1937, 1962 and 1987. Reese said Deere & Co. is providing a modern-day dealership replica.

The gathering also will include displays of some rare tractors, including a 1922 restored Waterloo Boy, a John Deere experimental Bathtub D, rare plows and an early corn planter.

The four-day event also will include more than 60 technical and historical workshops, 78 vendors selling items ranging from toys to tires, old parts and T-shirts.

Three evening speakers will provide various insights into John Deere and farm life. The presenters include Ken Buell, a retired Deere manager; Corey Rabe, a longtime Deere customer service representative; and Holly Spangler, associate editor of Prairie Farmer magazine and a farm wife.

The banquet keynote speaker will be Ray Defenbaugh, the 2010 Illinois Master Farmer and chief executive officer of Big River Ethanol in Burlington, Iowa. A special luncheon will be March 17 at the Hotel Blackhawk with Sally Lang, Deere & Co.’s manager for dealer licensing, as the guest speaker. She will discuss growing up in a John Deere dealer family as well as her experiences as a long-time Deere employee herself.

The gathering also will offer a variety of day bus trips to sites in eastern Iowa and western Illinois, including tours of John Deere factories in the Quad-Cities and Dubuque and Waterloo, Iowa; the Deere family homes in Moline; the Kenny Bush Museum in Milan; Big River Resources in Burlington; and an attachment distribution warehouse in Davenport.

“This has absolutely just mushroomed from 2000 when we had 750 people to 2010 when we had over 2,000 people from 37 states all over the country, Canada, the Netherlands and Australia,” Reese said.

The idea for the event began with Reese and co-chair Mark Johnson, who realized that there were national conferences for other tractor clubs, including International Harvester and Allis-Chalmers, but none for John Deere hobbyists. The men recruited four regional John Deere tractor clubs and launched the event, which received the “Host it Here” award in 2010 from the Quad-Cities Convention & Visitors Bureau.

Reese said the economic impact of the last gathering was $1.1 million for the Quad-City economy.

The clubs, which continue to help host the event, are Deere Valley Collectors from the Quad-City area; Northwest Illinois Deer Collectors Club; Northeastern Illinois Twin Cylinder Club; and Illinois Valley Two-Cylinder Club.

He said this year’s gathering is working to draw more Quad-Citians in the door for a day or a single event. “There are so many people with an agriculture background and John Deere-related people in the Quad-Cities. It’s kind of like a John Deere love fest; you see green and yellow every place you go,” he said.