Short Wave Predicting spring bloom is an art and a science
14 snips
Mar 31, 2026 
Elizabeth Wolkovich, a forest and conservation scientist who studies bloom timing, explains winter chilling and spring warming models. Matthew Morrison, an arborist with the National Park Service who cares for the National Mall cherries, describes the six stages of blossoming and local management. Aru Nair, reporter and on-site producer, narrates field interviews at the Tidal Basin. They discuss forecasting peak bloom, tracking thousands of trees, and climate-driven shifts.
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Park Staff's Humble Peak Bloom Story
- The National Park Service times the Cherry Blossom Festival to coincide with peak bloom to accommodate tourists and locals.
- Matthew Morrison remembers once nailing the date in 2019 but says he has never been right again, calling the prediction a "wild-ass guess".
Six Clear Stages From Bud To Full Bloom
- Cherry trees progress through six defined stages from dormant bud scales to full bloom, giving observers concrete markers.
- Matthew Morrison lists green bud, floret visible, florets extend, peduncle elongation, puffy flower, then full bloom as the sequence.
Bloom Timing Uses A Two Bucket Model
- Bloom timing depends on a two-bucket system: winter chilling and spring warmth, plus daylength influences.
- Elizabeth Wolkovich explains cherries need cold first, then accumulated warmth and longer daylight to trigger blooming.