Climate Fixers: Climate-proofing Philly for a warmer growing season

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Phil Forsyth is a pragmatist and wants us all to be prepared for a warmer future. And that future, he says, could mean bananas, kumquats and pomegranates replace some of the more traditional fruit trees that have thrived for centuries in the Philadelphia region.

“Some of our early fruiting crops like Asian plums and apricots, for example, increasingly break dormancy early; they bloom early and then they get hit by a frost,” Forsyth said.

That means those trees won’t bear fruit.

Forsyth knows a lot about fruit trees. He’s the co-director of the Philadelphia Orchard Project nonprofit organization and says he has seen lost crops more frequently as our winters become warmer.

“Some of our more northerly crops, apples and pears and things like that, need a certain number of chill hours. They need to be dormant for a certain period,” Forsyth said.

Forsyth said not all varieties of apples and pears will suffer, but the organization has several pomegranate trees producing fruit in the city and they are experimenting with some subtropical and Mediterranean fruits as well, including hardy citrus and bananas.

Behind the Woodlands Cemetery in West Philly, on the former softball field of the now defunct University of the Sciences, Forsythe checks the progress of these plants in an unheated greenhouse-like structure known as a high tunnel.

“It’s only using the sun’s energy,” Forsyth said. “It’s really a very simple structure. It’s a series of metal hoops with some plastic over it. And so, in the winter months, the sun comes through. The plastic captures that heat and keeps it a little bit warmer.”

But on a hot day in August, the plastic sheeting is rolled up and growing inside are an olive tree, a banana tree and a Chilean guava, along with hardy citrus trees like loquat, yuzu and kumquat.

Last fall, the U.S. Department of Agriculture updated its plant hardiness zone maps, which detail what crops will survive, thrive and overwinter in each region. Philadelphia was zone 7A back in 2012, but is now solidly in zone 7B, while parts of Delaware County are already in zone 8. Forsyth says zone 8 could be right around the corner for Philadelphia.

“The idea is to grow plants that are not quite viable outdoors, at least not yet,” Forsyth said. “So while we are officially zone 7B, these are zone 8 plants, which means essentially, they’re one zone further south. But we think in the decades to come, they may be viable outdoors in Philadelphia.”

In addition to preparing for a warmer planet, Forsyth says planting trees is one of the best ways to mitigate climate change.

The Philadelphia Orchard Project has planted more than 1,600 fruit trees across the city in vacant lots, school yards and gardens across the city. In 2023, those trees produced 11,700 pounds of fruit a year.

“We like to talk about the double carbon impact of urban orchards,” Forsyth said. “So fruit trees, like any other trees, are absorbing atmospheric carbon, but at the same time, all the food we produce in the city is food that doesn’t have to be produced elsewhere.”

And that, he said, prevents the additional fossil fuel use associated with industrial production, transportation and refrigeration.

“We feel this is an important approach to climate crisis mitigation,” he said. “So plant trees in your yard, plant them in vacant lots, this is the best tool we have to balance the climate crisis.”