Philly’s cherry blossoms were just entering peak bloom when a cold snap hit, likely freezing many of the delicate flowers that had already opened and putting buds in jeopardy. Horticulturists say bloom times are creeping earlier as the climate warms.
“I think because we’re earlier this year, there is a greater likelihood of these late frosts,” said Anthony Aiello, associate director of conservation, plant breeding and collections at Longwood Gardens. “In some ways, it’s kind of a funny year.”
The Japan America Society of Greater Philadelphia (JASGP), which runs Philly’s annual Shofuso Cherry Blossom Festival, predicted the city would be in “peak bloom” around April 1st, with the large collections of cherry blossoms along the Schuylkill River and West Fairmount Park reaching peak the next weekend, just in time for the festival. But warm weather in recent weeks accelerated the blooming process, said Shofuso head gardener Sandi Polyakov, pushing peak bloom earlier than usual.
Below-freezing temperatures like Philly experienced Monday and Tuesday can freeze the tissue of flowers that have already bloomed, causing them to turn brown and limp when temperatures warm up again. The full impact of Philly’s freeze on the buds that were ready to pop won’t be clear for a few days. Some might die and fail to bloom — or, they could be fine.
“We’re just going to have to wait and see,” Aiello said. “We were on track for a really nice display this year. And then, you know — it’s so unpredictable. I mean, these temperatures are extreme.”
The trees near the Horticulture Center in Fairmont Park and at Shofuso — including an iconic Japanese weeping cherry — look like they fared OK, Polyakov said.
“Fingers crossed that the cherries in West Fairmount Park will bloom this weekend,” he said Tuesday. “But I won’t know for sure, for like two days. They could have gotten toasted.”
As the climate warms, a trend toward earlier blooms — but lots of variability
During a warm spring last year, the cherry blossoms in Kyoto, Japan peaked the earliest they have in 1,200 years of records — fitting into a trend of earlier bloom times that experts said was an indicator of climate change. Warmer winters can also cause cherry trees to bloom later, since they need a full month of chilly weather to properly “wake up” when it gets warmer.
Peak bloom dates are always subject to variation, tied to particular weather patterns of a given year, Polyakov said. But local experts agree there’s been a trend toward earlier spring blooms in the Philly region.
“When I came to this area in 1986, I would say the earliest cherries and earliest magnolias were [blooming in late March or early April],” said Andrew Bunting, vice president of public gardens and landscapes at the Pennsylvania Horticultural Society. “Then with global climate change and warming winters, it has been creeping back. At first it was like a day or two here — but now … it has been sped up by two to three weeks, which is a lot given it’s only been 30 years.”
Winter is the fastest-warming season across Pennsylvania and most of the United States. Philly’s average winter temperature has risen nearly 5 degrees Fahrenheit since 1970.
Bunting has also noticed more southern varieties of spring-blooming plants, like camellias and magnolias, thriving in Philly.
“Thirty years ago … there were a couple that kind of limped along and looked okay,” he said. “But now I would say every southern magnolia is 100% viable.”
Growing a diversity of flowering trees and plants will be key to maintaining gorgeous spring blooms in Philly as the climate warms, Polyakov said. “It does help you hedge your bets.”
Don’t despair! More blooms are on the way
Even if this week’s coldsnap put a damper on Philly’s “peak bloom,” it likely won’t hurt the cherry trees expected to flower later this spring.
The idea of “peak bloom” is a bit misleading anyway, Polyakov said. It’s focused on the Yoshino cherry variety, which blooms along the Tidal Basin in Washington, D.C. But several different varieties grow in Philly, including the pink and magenta Okame, which blooms earlier, and the bubblegum pink Kwanzan, which blooms later.
The frost likely meant the end of the Okame bloom, Polyakov said, but Philadelphians can still expect a full flowering of Kwanzan and other late-blooming varieties, as well as a smattering of Yoshino and the more variable Higan cherry.
There are plenty of places around the city and the region to see the spectacular blooms. Flowering cherries are a popular street and park tree, Aiello said, so start by looking around your neighborhood.
If you want to make a trip of it, here are some of the spots horticulturists recommend.
- Kelly Drive on the east bank of the Schuylkill River near the Art Museum
- MLK Drive on the west bank of the Schuylkill
- Shofuso Japanese House and Garden in West Fairmount Park
- Morris Arboretum in Chestnut Hill
- The Navy Yard
- Scott Arboretum at Swarthmore College
- Tyler Arboretum in Media
- Chanticleer Garden in Wayne
- Longwood Gardens in Kennett Square
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