Phenology Study at the Demonstration Garden

By Bob Shaw, MCMGA Master Gardener
May, 2022

We are beginning what we hope will be an annual survey aimed at understanding the relationship between the bloom times of Pacific Northwest Native woody perennials and pollinator abundance and diversity. At the demonstration garden we now have 15 species of native shrubs and understudy trees that are sufficiently mature for inclusion in the study, and we have several recently planted shrubs that we can add in coming years.

Study participants observe a flowering plant for five minutes when pollinators are active (i.e., when the ambient temperature is 70°F or higher) and record their observations in a logbook. As we are not entomologists, we use a simplified procedure: we divide pollinators into three groups—European honeybees, bumblebees, and native bees. If other invertebrates (e.g., butterflies) we will note this as well.

People who garden to preserve native pollinators plant a variety of woody perennials, herbaceous perennials and annuals in order ensure a succussion of blooms from early spring until mid- to late- October. One goal of our study is to understand the relative value of woody perennials to native pollinators. A secondary goal is to begin to understand the extent to which honeybees and native bees compete for native plant resources. As our bee-identification skills increase, we also hope to identify associations between specific shrubs and specific native-bee species.

The results of our study will be anecdotal—not scientific. We hope, though, that our observations will spur more rigorous research studies. One thing is certain: study participants will become familiar with native shrubs and enjoy observing pollinators on them. If you would like to join us, come to the Demonstration Garden on any Wednesday from 9:00 a.m. to 12:00 p.m. Tom Ralley and I will explain in greater detail how the study works. We welcome your participation.