It shouldn’t come as a surprise that the Common Ground Fair finds common ground when selecting the art for its promotional posters.

“It’s not a written policy, but for a long time now it’s been animals on even-number years and vegetables on the odd-number years,” Maine Organic Farmers and Growers Association Executive Director Russell Libby explained.

“I think it’s because we have a strong division of both among our members,” Libby added with a chuckle. “If the animal people have a winner one year, the vegetable people will want one the next.”

MOFGA has been holding the Common Ground Fair since 1977. For the first five years the fair was held at the Litchfield Fairgrounds. It’s been at the Windsor Fairgrounds since 1982. This year’s celebration of the harvest and Maine agricultural products begins on Friday, Sept. 22.

Just as the fair has expanded from a modest gathering of a few thousand people that first weekend 19 years ago to an eagerly awaited event attracting upward of 70,000 these past few years, so has the quality of the fair’s poster art.

The original poster, a framed heirloom displayed prominently on Libby’s office wall, was a simple design with block lettering listing exhibitors and guest speakers. This year’s poster features a vine of cucumbers in various shades of green. Artist Joan Schultheiss’ winning design was selected from more than 60 entries. Many well-known Maine artists have submitted work to what has become a hotly contested annual competition. MOFGA awards a $500 prize to the winning artist.

“It’s a very open process and any citizen of Maine can take part. The only rules are that it be an agricultural theme and that they do a polished drawing,” Libby said.

Along with the fair, its poster art also is a growing phenomenon throughout Maine and the Northeast. This year, Schultheiss’ cucumbers art will be displayed on 3,000 posters and more than 10,000 T-shirts.

“Although a lot of people have framed their favorites, most of the posters go out in the form of shirts,” Libby said. “Not too many people put them on their walls but an awful lot are wearing them.”

The shirts are printed at Liberty Graphics in Liberty, and owner Tom Opper said some design changes are usually required to convert an artist’s concept to a design compatible to silk-screen painting on cotton shirts. “It’s very important whether it is a good looking T-shirt or not.”

Libby echoed that observation. “We sometimes ask artists to do certain things like add highlights and colors or embellish their design. Usually they are changes to make it stand out a little more in terms of a poster or shirt. Our most successful posters have also been some of our most successful T-shirts. There’s got to be bright colors and something that both men and women would like to wear.”

The winners are selected by committee a year before the posters and shirts go to print. Schultheiss, an illustrator and graphic designer from Portland, said even though a year has passed since being selected and her poster going on display, the excitement of winning had not faded.

“It’s almost like a surprise to see it come out a year later. It was very exciting last year when they picked it. A lot of people have seen it and have recognized that it is my style. I definitely think that it will help my business in the long run,” she said.

Schultheiss said she thoroughly enjoyed working with the committee and finding ways to revise her original illustration to accommodate MOFGA’s needs.

“They are a great group of people at MOFGA,” she said.

Among the more popular posters produced over the years were Dahlv Ipcar’s 1987 collage titled “Country Crossroads,” a panel of which was reproduced on a T-shirt; Beth Pritchard’s 1989 bunch of carrots; and D.D. Tyler’s “blissful pig” with its upturned grin.

“Usually you get one or two that clearly are attractive to everybody, not necessarily the subject but the way the art was done,” Libby said. “There is a commercial aspect in this. You can’t have a poster that no one is going to want or a T-shirt nobody wants to wear.”

As for the habit of featuring animals one year and vegetables the following year, Libby said that selection of the winning poster for the 1996 came close to bringing that trend to an end when MOFGA’s poster committee voted last week.

“All the vegetarians were pushing for a vegetable,” Libby revealed.

The final vote was 7-5 in favor of a head-on view of a team of mules. The winning artist was Fran Goodine of Canton.