Climate change is altering global temperature patterns and triggering phenological shifts,
including advancements in breeding events and changes in growth. Flowering in plants acts as an
indicator for phenological shifts and is therefore a measurable response to changing
environmental cues. Research on wildflower bloom time in response to warming climates has
been conducted in many parts of the world, often using herbarium records as a historical
reference. Our research compared observed first bloom dates of 22 wildflower species at the Pine
Hill Arboretum in Enola, PA from 2018-2022 with arboretum records from 1935-1944. The goal
of the study was to quantify changes in wildflower bloom phenology over the 87-year timespan.
This is the first study of wildflower bloom times to be conducted in South Central Pennsylvania
and is unique in that historical records of first spring wildflower bloom can be compared at a
preserved study site. Results indicate that the first bloom date for 11 of the 22 species is
advancing significantly and all species experienced a significantly fewer accumulation of heating
degree days during overwintering. Ultimately, first bloom of spring wildflowers has advanced
10.2 (±7.42) days which equates to approximately 1.17 (±0.85) days per decade. Observed trends
are expected to become more apparent with further surveying of first bloom dates at the Pine Hill
Arboretum. Phenological changes, such as advancing first bloom, have the potential to affect
pollinators, the trophic cascade, and relative abundances of native and naturalized species