In her years as Philadelphia’s tree czar, Joan Blaustein has heard all the reasons why some residents persistently refuse to plant trees. Trees are messy; they drop leaves. They destroy the pipes. They drop leaves in the pipes. They lead to crime because muggers hide behind them, and burglars climb up them and into second floor windows. None of this is true (well, except for the leaf-dropping part). But that hasn’t stopped some Philadelphians from continuing to insist it is.

“The level of resistance some people in Philadelphia have to trees is shocking,” says Blaustein. “It’s a very strange phenomenon that people don’t understand the enormous benefits that a tree will give you.”

Blaustein, director of the Urban Forestry and Ecosystem Management Division in the city’s Parks & Recreation Department, came here from Pittsburgh in 2006, just in time to be part of the legacy of Michael Nutter’s mayoralty: Greenworks, his grand plan to make Philadelphia greener and more sustainable. The most visible part of that plan is also what would seem to be the simplest: Plant trees—a lot of them.

A 2010 survey of the city found that Philadelphia has a 20 percent “tree canopy”—which means 20 percent of the city is covered in green, as seen from above. Greenworks’ goal is to have a 30 percent tree canopy, in every neighborhood and overall, by 2025. (Right now, the Northwest has 80 percent, while Chinatown has 3 percent.) This is not just about making Philadelphia more beautiful. Trees are our best defense against the ravages of climate change. Already, the city’s 2.9 million trees store about 2.6 million tons of carbon dioxide; remove 513 tons of air pollution every year; and reduce residential energy costs by $7 million a year. A big tree can hold thousands of gallons of water on its surface, helping to reduce flooding. And trees also raise property values: Houses on streets with a lot of trees see a 10 percent boost in their sales price.

“For cities to survive and thrive into the future, they have to have natural resources in place to combat climate change,” Blaustein says. “Trees are the least expensive and biggest way to do that.”

The city’s approach to tree-planting under Greenworks has been two-pronged. Blaustein says her crews have planted thousands of trees in parks and open public spaces throughout town. But the city realized early on that the only way to accomplish its goals was to put more trees on private sidewalks and back yards. They launched TreePhilly to give away yard trees a couple times a year, and sidewalk trees in front of the houses of any residents who requested them. Those programs have become more refined and widespread—neighborhood groups often deploy volunteers to help plant yard trees, and city contractors who plant sidewalk trees are now required to water and inspect them for a year. “We understand that people don’t want to take responsibility for a new tree,” Blaustein says. “This way that’s no longer an inhibitor.”

Twenty percent of Philadelphia is covered in green, as seen from above. The goal is to increase that to 30 percent. Trees are our best defense against the ravages of climate change. Already, the city’s 2.9 million trees store about 2.6 million tons of carbon dioxide; remove 513 tons of air pollution every year; and reduce residential energy costs by $7 million a year.

There has been success: According to Greenworks’ 2015 Progress Report—the last of Nutter’s administration—the city has planted 120,000 new trees since 2009. Unfortunately, we have also lost thousands of trees due to storms, disease or damage. Though the next tree canopy survey in a couple years will show progress, the tree-ification of Philly has been more haphazard than Blaustein would like. For one thing, there’s the antipathy towards trees among residents in some neighborhoods—like South Philly, where the announcement of Greenworks launched a debate in the South Philly Review about the perils of these “lions.”

But there’s also a more bureaucratic reason: Chicago, Washington, D.C., New York and most other large cities have tree management databases to keep track of their urban forests. Not so Philadelphia. In D.C., for example, chief arborist Earl Eutsler can call up on his computer a comprehensive database of every single tree; its condition; when it was planted (if recent); when it was last inspected and is next due for a checkup; what work was done; what calls the city has gotten about it; and what other trees are nearby. D.C. is already the most tree-filled city in the country—it has a 37 percent tree canopy. Now, Eutsler’s goal to fill every single available tree space in the Capitol is actually attainable—because his management system allows him to map out the exact locations, to the address, that still need a tree.

Blaustein, on the other hand, has an Excel spreadsheet. “We don’t know what’s going on unless our inspectors go out to see what’s there,” she says. “We can’t make the case that we have 10,000 dead trees out there and need the money to replace them because we don’t know. That’s a great deficit.”

A tree “asset management system” like that in D.C. would cost Philadelphia $1 million—money Blaustein says she has asked City Council and the Nutter administration to authorize for the last several years. No one—not even the eco-Mayor—has made an effort to cough it up. “I take responsibility for not being able to make a strong enough case,” Blaustein says. “I  keep reminding people of why it’s important to fund this, but so far they haven’t done so.”

That’s too bad. A million dollars seems like a lot. But Eutsler points out that his system—in place since 2006—has more than paid for itself. “Trees are the only infrastructure improvements that gain in value over time,” he says. “As they get older and bigger, they deliver geometrically increasing environmental and economic benefits. The return on investment is taken care of.”

A tree “asset management system” like that in D.C. would cost Philadelphia $1 million—money Joan Blaustein of Parks & Rec has asked for. No one—not even the eco-Mayor—has made an effort to cough it up. “I take responsibility for not being able to make a strong enough case,” Blaustein says.

Eutsler’s work is made easier by a couple of other D.C.-specific rules. When architect Pierre Charles L’Enfant laid out the city in 1791, he incorporated trees into the areas that are now sidewalks, which means there are designated spots going back 200 years where there’s supposed to be a tree.

More recently, D.C. promised the Environmental Protection Agency to plant 4,150 new trees as part of a water abatement system. Eutsler says city workers use both those mandates to inform reluctant residents that they’re planting a tree, not ask them. “We overwhelm them with trees,” he says. “What we’ve noticed is that as people are increasingly surrounded by trees, they have a desire for more. There’s this tipping point where areas with very few open spaces clamor for things to be planted, and areas with no trees can go all year without one request.” (How does he know this? By analyzing his data.)

In Philadelphia, Blaustein must wield a softer stick. But she says she’s hopeful about the urban forest she’s helping to grow. Already, she’s seen that as newer residents move into town, the old prejudices against trees have started to fade, at least in certain neighborhoods. And like in D.C., reluctant residents often change their minds once their cold winters are brightened by spring blooming. “Even people who don’t want them see how beautiful trees look in spring,” Blaustein says. “The tree makes its case for us.”