Plant phenology is the study of when plants do some visible
act in relationship to the calendar or clock. For example, spring snowdrops
usually come into bloom in late March or early April. During Victorian times plant phenology was
taken to its highest levels, almost becoming an art form. As Victorian era
gardeners planted massive carpets of annuals in intricate designs, they also
began a tradition of planting floral clocks; literally a planting of flowers
which could be used to tell the time (or at least approximate the time).
Going back to phenology, we’ve all noticed that certain
plants open their flowers at various times through out the day. For example:
morning glories, moon flowers, four-o-clocks, evening primrose and daylily
to name just a few. It’s this
phenological characteristic that was used to create these intricate and surprisingly
accurate floral clocks.
Now we may no longer plant flower clocks and our busy
schedules may not allow us the luxury of keeping our own phenological records,
but plant phenology can still play an important role in our industry. Close observations of when certain events
occur are becoming more and more useful in the control of many plant pests.
Let me give you just one example. Bronze Birch Borer (a widespread and possibly
fatal insect of paperbirch) is best controlled by certain chemicals when the
lilacs are in bloom. Applications of these same chemicals at other times to
control the borer are mostly ineffective.
Lilac time is a simple observation which can allow you to better control
a pest problem and lessen useless applications of hazardous materials into our
environment. So next time you “stop to
smell the roses,” maybe take a few notes or observations as well.
