After 20 years and more than $7 million in corporate support, PNC Bank has ended its big-time commitment to the Philadelphia International Flower Show, bank and show officials confirmed Thursday.

"It was and is a great relationship, but we thought it was an ideal time for us to diversify some of the sponsorships that we do in Philly and are contemplating doing," said J. William Mills 3d, PNC's regional president for Philadelphia and South Jersey.

Mills remains on the board of the Pennsylvania Horticultural Society, which wrapped up the 2011 Flower Show on March 13 with its highest attendance in nine years. He said the bank would continue to financially support and work with the horticultural society, though not in the same way.

"We are not abandoning PHS," Mills said.

Drew Becher, president of the horticultural society, said he was exploring potential corporate partnerships across the region and nation and hoped to create attractive packages offering benefits to the companies and the horticultural society, which has produced the Flower Show since 1829. Becher knew when he took the job in 2010 that PNC's sponsorship was winding down.

"I don't ever think one size fits all. There are so many ways the Flower Show can work with companies," Becher said.

Three companies might share lead sponsorships, he said. Others might want to underwrite exhibits or appearances by celebrity gardeners, or support bringing exhibits to the Philadelphia show from the Royal Horticultural Society's famed Chelsea Flower Show in London.

Still other sponsors could be involved with Plant One Million, an ambitious plan to plant a million trees in Pennsylvania, New Jersey, and Delaware over the next few years. At this year's show, which cost about $8 million to produce, Becher announced that the horticultural society would coordinate the effort, which is similar to a program he headed in New York City.

"I'm looking forward to having new partners to push us in new directions, to do something bigger and better," Becher said.

Pittsburgh-based PNC, which has been the Flower Show's primary, or presenting, sponsor since 1992, quietly told the horticultural society in June 2009 that 2011 would be its last year in that role, Mills said.

Around the same time, Jane Pepper, Becher's predecessor, announced that she would retire from the horticultural society in mid-2010 after 30 years, 25 as president.

"We had been with Jane the entire time. That was a great relationship, and it was sort of coincidental that she was retiring around the same time," Mills said, adding that PNC gave early notice of its decision "so as not to leave Jane's successor in the lurch."

For her part, Pepper called PNC "terrific supporters for those 20 years. I think it's an amazing thing that they were there that long. That is very unusual in the field of sponsorship."

As the show's major sponsor, PNC not only provided financial support, but also mounted a large exhibit every year, wined and dined customers at the show, conducted behind-the-scenes tours for special groups from the bank, and, Pepper said, "generated community support and enthusiasm for the show.

"Obviously, it was great for us to partner with them," she said.

Before being recruited for the horticultural society job, Becher was executive director of the New York Restoration Project, a high-profile endeavor founded by actress and singer Bette Midler to improve New York City's parks, neighborhood gardens, and open spaces.

There, Becher was known as a prodigious marketer and fund-raiser. He raised $6 million for revitalization projects, lined up big-name sponsors such as Toyota and Home Depot, and managed the nonprofit like a business with many services and varied customers.

He vowed to do the same in Philadelphia, which the horticultural society search committee mentioned as a key factor in his selection.

Becher cited the regional economic impact of the Flower Show - $61 million a year, according to the auditing firm KPMG L.L.P. - as a huge enticement for corporate sponsors. So, he said, is the idea that the show supports the horticultural society's many garden and greening programs.

Despite the economy, 2011 attendance was 265,000, a 12 percent increase over 2010, according to the horticultural society.

"I'm very confident we'll have new partners in place for the 2012 Flower Show. Just watch," Becher said.

Though the 2011 production was the best-attended since 2002, it also provided PNC with an unusual - and unpleasant - send-off: For the first time, protesters disrupted the show, and they chose the bank as their target.

Members of a group called the Earth Quaker Action Team held hands and formed a human chain in front of PNC's "green wall" exhibit to protest what they termed the bank's environmental crimes in Appalachia.

Though it may have been embarrassing, the protest had nothing to do with PNC's decision to end its megasponsorship. "Not at all," Mills said. "The decision had been made a while back."