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March 8, 2024

Video: Predicting cherry tree bloom timing at the UW

[March 26 update: Peak bloom is set to continue at least through the weekend of March 30-31, according to UW arborist Sara Shores. “The cool weather is helping now,” said Shores. “I believe the blooms will be hanging on into the weekend. The leaves are close and once the leaves begin [to emerge], the blooms are harder to see.”]

[March 20 update: As peak bloom continues, this post was updated to include a video about an ongoing study of the UW cherry trees and the headline was changed from “UW cherry blossoms set for peak bloom in late March” to “Video: Predicting cherry tree bloom timing at the UW”]

[March 19 update: Cherry trees in the UW Quad are at approximately 70% bloom and have entered “peak bloom” stage. “If the weather stays cool, with little wind or rain, the bloom should last about two weeks,” said Autumn Maust, a UW doctoral student in environmental and forest sciences.]

[March 18 update: Thanks to unseasonably warm weather over the weekend, approximately 50-60% of buds on the UW Quad cherry trees are now in bloom, with peak bloom expected to begin by March 19 at the latest.]

[March 15 update: All trees in the Quad now have pink buds with some florets visible. Approximately 2% of buds on the UW Quad cherry trees are now in bloom.]

[March 13 update: All cherry trees in the Quad are now at the “peduncle elongation” stage of bud development, during which the stalks supporting the florets grow longer. It is one of the last stages before the florets open.]

Cherry trees on the University of Washington’s Seattle campus are waking up and getting ready to say hello. For the 29 iconic Yoshino cherry trees in the UW Quad, peak bloom will likely begin after March 20, according to UW arborist Sara Shores.

“Historically, peak bloom in the Quad typically begins during the third full week of March and goes into the fourth week of March. That seems to be what this year is going to look like,” said Shores. “Right now, I would guess that the last two weekends of March are ideal viewing conditions.”

This post will be updated with the latest estimates, which could change based on weather conditions.

Cherry tree fans don’t have to wait for peak bloom to visit campus. The entire cherry blossom season is a great time to visit and see the trees in bloom.  The UW maintains a visitors’ website dedicated to the school’s cherry blossoms, providing tips for getting to campus and maximizing the tree-viewing experience. The site has updates on the status of the blooms as well as details on transportation, activities and amenities. The Quad cherry blossoms also have their own social media accounts on Instagram and X, formerly Twitter. For cherry tree enthusiasts who can’t make the trip, campus webcams are a good option for virtual viewing.

The timing for peak bloom — meaning 70% of buds have emerged — varies each year based on weather conditions that the developing buds are exposed to in January, February and March.

“In order to reach peak bloom, buds need to accumulate a certain number of both cold and warm days, known as ‘growing degree days,’” said Marlee Theil, a UW graduate student in the School of Environmental and Forest Sciences.

As of March 8, just over half of the cherry trees in the Quad were at the “peduncle elongation” stage of bud development, during which the stalks supporting the florets grow longer. It is one of the last stages before the florets open and the bloom season begins. The remaining cherry trees in the Quad are also progressing normally, albeit one or two days behind.

Since 2018, a UW research group has been monitoring campus blossoms from January to April with the goal of creating a model that will use weather data to predict the timing of peak bloom. Theil currently leads the monitoring team of more than 20 undergraduates.

“The data that we gather will not just help us know in future years when to come to campus to enjoy the trees,” said Theil. “This will also be a valuable research tool to understand how these trees respond to changing environmental conditions.”

There are more than 100 cherry trees on campus. The main species is Yoshino, including the trees in the Quad. Other varieties include the Higan, Hisakura, Kwanzan, Mt. Fuji and Shirofugen trees that can be viewed at locations across campus. The Yoshino trees bloom earlier than many of the other species.

“Even as bloom season wanes for the Yoshino trees in early April, other trees on campus will be starting,” said Shores.

How long blossoms will remain on the trees this year depends on the weather. Cooler temperatures, less rain and lighter winds all will help keep blossoms on the trees.

For those who wish to avoid crowds on the Quad, visiting on weekdays and in the early mornings are better options. The UW asks that visitors not climb the trees, move their branches or shake their branches, as this can cause damage.

Visitors are encouraged to share their photos by using the #uwcherryblossoms hashtag.

For media inquiries about the cherry trees, contact James Urton at jurton@uw.edu or 206-543-2580. For broadcast media, b-roll and photos from past years are available.

Tag(s): Autumn Maust • cherry blossoms • College of the Environment • Sara Shores • School of Environmental and Forest Sciences

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