Nearly 10 years ago, on Dec. 21, 2001, a fire roared through the store in the middle of the night, destroying the business and all that season's Christmas orders, lined up ready for delivery.
The store reopened after 11 months, surviving only to be walloped by the recent recession.
"These past few years we've come under hard times like everyone else," Kelly said. "I think I've taken five days off in the last three years."
Maybe there is a difference between a business and a calling, but that hasn't dawned on Kelly.
The business is the side the accountants see, with, in Stein's case, hundreds of thousands of dollars of debt and an owner, Kelly, who now pays himself and his wife less than what one of them earned in better years.
Kelly sees it differently.
To him, the business on Frankford and Princeton Avenues is not just some storefront in a blue-collar neighborhood's shopping strip.
"I feel like I'm the caretaker of this 127-year-old Philadelphia tradition," he said. "It's like a museum and I've been empowered to keep it going.
"We are taking care of customers who are 80 years old and got their prom flowers here," he said.
"I will continue to sacrifice to make a living here," he said, quipping that an accountant once told him, "you are buying yourself a very expensive job."
Maybe some entrepreneurs build businesses to flip them, but again, that has never been Kelly's plan.
"My childhood," he said, "was meager, very meager."
When he was 17 years old, he got a job at a florist's shop in Cleveland. His work ethic, he said, made him the protege of the owner, who trained him in floral design. He also met his wife, Janet, there.
They married at age 19, and by 21 had moved to Philadelphia to work at Stein's. The owners, Joseph and Celia Stein, were also impressed by Kelly and promised to turn the business over to him.
For a while, it looked as if the Steins' grandson, Dan Stein, would end up with the business instead.
But the two men worked out a deal, and a friendship, with Kelly owning the business and Stein financing it.
Stein's, with its classic '50s architecture and neon signs in a modest neighborhood, and with a second store in Burlington, does the following: It supports Kelly, his wife, two grown daughters and 30 employees - all earning, he said, a wage that can sustain them, with all full-timers offered health insurance.
And, all day long, every day, he works with his wife and daughters, Jennifer, 24, and Jessica, 27.
"Our lives are unfolding here," Kelly said.
The girls were in their teens on Dec. 21, 2001, when the phone rang in the middle of the night: An emergency - the Stein's store in Mayfair was on fire.
When Kelly had left at 10:30 p.m., just a few hours earlier, every inch of Stein's had been packed with flowers ready for delivery the next day - four days before Christmas.
Hundreds of poinsettias for churches, gorgeous flower arrangements decorated with ribbon and tinsel. No wonder the fire burned so hot and the smoke was so dark.
"When we got there, the place was black. The heat was so intense, the computer keyboards melted to the desks. The soot was intense. Then the firefighters smashed out the windows," he said. "It was devastating. I put my head down and sobbed like a baby.
"We had to make a decision about whether to surrender it," he said.
Gone would be his livelihood, certainly, and there would be no work for many of the three dozen employees who depended on the business to raise their families.
Through the night and into the morning, the employees began to show up. "It was horrible," said Brian Knipp. "My heart just dropped. It wasn't pretty. The smoke was billowing out. It was freezing."
Covered in soot, standing in the ruins of the store, Kelly promised his full-time employees that he would rebuild and that he'd pay them in the meantime. Insurance covered a lot, but in the end, it would cost $260,000 more to reopen, money bankrolled by the Steins' grandson, money that Kelly now owes him.
" 'Don't worry, I'll take care of you,' " employee Arlene DiFiore recalled Kelly saying. And sure enough, every week, they'd meet on the sidewalk outside the store and he would hand out paychecks. "You don't find many bosses like he is. I'm happy here."
The fire was the big dramatic moment in this business' history, but day-to-day survival depends on many small adjustments to a changing economy and a changing clientele.
For example, Stein's always had a big funeral business. Last week, as is typical, they built a policeman's badge out of flowers as part of a floral array for a retired law enforcement officer who died.
But the recession has prompted people to choose less-costly cremations instead of full-fledged funerals. "Cremations translate into smaller arrangements," said Kelly's daughter, Jennifer.
That's why, this summer, the family plans to learn how to make the kinds of garlands that families from India buy for important occasions. And Stein's is getting more business from Chinese customers, who want very elaborate, highly stylized arrangements, each one different.
During the recession, Kelly said, everyone cut back.
Weddings were smaller, and so were bouquets and centerpieces. Young men still courted sweethearts with roses, but a single stem would have to do.
Last week, though, in a sign that the economy is blossoming again, someone ordered five dozen roses in five different colors for someone named Ambria. "We're buying more roses," Kelly said.
"The flower business," he said, "always seems to sustain itself in bad times."
Or, maybe there's something else:
"A passion for what you are doing," Kelly said. "I never lost faith in the fact that good works and good citizenship means that good things will happen to you."
Contact staff writer Jane M. Von Bergen at 215-854-2769 or email@example.com.