"You were taking a tree . . . and having it be around for a month, and then having it go into the landfill," she said. "I thought there had to be something better to do."
Five years ago, Kelly, the Northern Liberties Neighborhood Association's "clean and green" coordinator, contacted Bartlett Tree Experts in Bala Cynwyd, and it agreed to help. Neighbors brought 300 trees to a central location to be chipped, then spread in a local dog park.
Other associations caught wind of the project and called Kelly, hoping to join in. Now more than 20 groups are involved in 10 "treecycling" events in the city. Last year, they processed 3,000 trees.
For Kelly, the goal is "not about not having a tree. It's to handle things responsibly. Everybody wants a Christmas tree, but put it back to the earth, instead of putting it onto the mountain of trash."
Equipment arrives in involved neighborhoods on specified days - this season, Jan. 4 and 5 - and families haul out their trees to be chipped and used as mulch or compost at community gardens, school landscapes, dog parks, and other neighborhood areas.
Two more companies, Schectman Tree Care of Philadelphia and All Seasons Landscaping of Aston, are participating, too.
Kelly said the companies provide the equipment and the groups pay the operators out of donations - $5 per tree is requested, but she said many people give more just to support the effort.
"There's something depressing about seeing Christmas trees on the sidewalk, being thrown out," said Michael Resnic, who helped start the Logan Square Neighborhood Association's program.
The Logan effort, held in a parking lot, offers drive-through service; people don't even have to get out of their cars.
But they might be missing out.
In other neighborhoods, tree-chipping day becomes a mini-community celebration.
"The kids are fascinated by the chipper," Kelly said. "They'll watch the tree go in, then run down the other end and see the chips."
The flip side: "Some of them get upset. That was their Christmas tree, and now it's in a million pieces. Tears are involved."
The events also make the weekend one of the most fragrant of the year. "It smells so fantastic in the neighborhood," Kelly said.
From Collingswood to Havertown, in Warrington and across the country, curbside pickup and mulching of trees is a commonplace part of year-round efforts by municipalities to compost yard waste instead of landfilling it.
Cheltenham, for instance, has a four-day blitz, two days on each side of the township. But Christmas trees inevitably turn up curbside afterward, said highway superintendent Chris Clewell. Puzzled workers have seen them in July.
Nationwide, about 25 million live Christmas trees are sold, and tree recycling has become so routine that the National Christmas Tree Association no longer keeps a database on it, said spokesman Rick Dunleavy.
"Public sector, private sector, nonprofit groups . . . programs involve all kinds," he said.
Recycled Christmas trees have been used for a heron nesting area in Illinois and fish habitat on a New Hampshire lake.
The Louisiana National Guard turns treecycling into a training exercise, air-hauling trees to a marsh-preservation site.
It's common for New Jersey communities to stack old Christmas trees on the dunes to capture sand, an effort that took on new urgency after Hurricane Sandy.
Philadelphia revived tree recycling in 2007, but only as a drop-off program at city sanitation centers. Last year, residents dropped off about 1,500 trees, and they were delivered to a private vendor for composting.
That's half of what the neighborhood volunteers handled. More important, perhaps, it's when people actually see their trees turned into mulch that "they really begin to understand sustainability and the tremendous power they have as consumers," said Lauren Leonard, editor of the blog Greenlimbs.com. And for the sustainably-minded set, "treecycling eases the guilt some feel for having a real tree," she said.
Leonard, who helped organize a South Philadelphia event that is separate from Kelly's network, hopes the concept continues to spread. "The goal," she said, is to "make Philly a place where no tree has to end its life on a cold, concrete curb."
'Treecycling' in Philadelphia
Here is the schedule for civic-association chipping events. A $5 donation is requested.
Kensington/Fishtown: 9:30 a.m. to 12:30 p.m.; Palmer Dog Depot, East Palmer Street.
Northern Liberties: 10 a.m. to 4 p.m.; Liberty Lands Park, North American Street.
West Philadelphia: 10 a.m. to 4 p.m.; Clark Park, Baltimore Avenue.
West Center City: 10 a.m. to 4 p.m.; Markward Recreation Center, 400 S. Taney St.
South Philadelphia: 10 a.m. to 4 p.m; 13th and Reed Streets. (Greenlimbs.com also is organizing sites: 9 a.m. to noon, Weccacoe Playground, Catharine Street, collection only; and 9 a.m. to 4 p.m., Whole Foods Market, 10th and South Streets.)
Logan Square: 9:30 a.m. to 12:30 p.m.; parking lot at 22d and Winter Streets.
Fairmount/Art Museum: 1 to 4 p.m.; 22d and Brown Streets.
Chestnut Hill: 9:30 a.m. to 12:30 p.m.; Norwood- Fontbonne Academy, 8891 Germantown Ave.
Mount Airy: 1 to 4 p.m.; Gabbie's Community Garden, Chew Avenue off Mount Pleasant Avenue.
East Falls: noon to 4 p.m.; Ridge Avenue and Scotts Lane.
City drop-off program
From Jan. 6 to 18, Philadelphia residents may drop off their undecorated trees at the Streets Department's Sanitation Convenience Centers at 3033 S. 63d St.; Domino Lane at Umbria Street; and State Road at Ashburner Street. The centers are open from 8 a.m. to 6 p.m. Monday through Saturday.
In the suburbs
Many municipalities in Pennsylvania and New Jersey have recycling programs, including curbside pickup of Christmas trees. Check with local governments.