Field Observations

Phenology Log

Ground-truth phenological observations from across the Puget Sound lowlands, paired with Growing Degree Day accumulations. Each observation anchors a species to a point on the season's thermal curve.

Current GDD₃₂ (Kent): 874 as of March 18, 2026

5
Observations
5
Species
2
Event Types
1
Stations
GDD₃₂ Scale
864 Now: 874
March 2026
Thu, Mar 19
958 GDD₃₂
🌱 leaf push BBCH 10
Parrotia persica 'Vanessa' · Persian Ironwood
Issaquah Confirmed
Leaves just emerging. GDD₃₂ estimated (Mar 18: 937.4 + ~20/day trend).
Tue, Mar 17
914 GDD₃₂
~est.
✿ first bloom BBCH 61
Prunus salicina 'Santa Rosa' · Santa Rosa Plum
Issaquah Confirmed
Started blooming 2 days ago as of Mar 19. No profile yet for this cultivar.
Tue, Mar 17
914 GDD₃₂
~est.
🌱 leaf push BBCH 10
Syringa vulgaris · Common Lilac
Issaquah Confirmed
Leaf push starting in last 3 days as of Mar 19. Conversion file predicts first bloom at 973 GDD₃₂ / Mar 25 - leaf push before bloom is consistent.
Mon, Mar 16
895 GDD₃₂
~est.
Red Flowering Currant first bloom observed 2026-03-16
✿ first bloom BBCH 61
Ribes sanguineum · Red Flowering Currant
Issaquah Confirmed
Started blooming this week as of Mar 19. Key PNW native indicator species.
Sat, Mar 14
864 GDD₃₂
~est.
Red Maple first bloom observed 2026-03-14
✿ first bloom BBCH 61
Acer rubrum · Red Maple
Issaquah Confirmed
Started blooming in the last 6 days as of Mar 19. Midpoint ~Mar 14. Conversion file predicted 552 GDD₃₂ / Feb 22 - was 35% low.

Observations are recorded by Chris Welch (ISA Certified Arborist) during regular field surveys across the Puget Sound lowlands. GDD₃₂ values are paired from the nearest weather station. Over time, these observations calibrate the GDD thresholds in each species profile.

5 observations logged as of March 20, 2026.