by Sharon Morrisey, consumer horticulture agent in Milwaukee county

Phenology is a branch of science that studies the relationships between natural events and weather, especially temperature, rather that specific calendar dates. For gardeners, these events may be plant emergence, budding, flowering, or fruiting. Keeping records of these events on your own property can tell you each year how near normal the season’s overall progress is.

By observing the relationship between discrete phenological events and the season, seemingly unrelated events can be correlated. Through years of record keeping, seasonal development of certain common, recognizable indicator plants has been correlated with the development of common insect pests and can be used to determine when outbreaks of these pests are likely to occur. Insects are particularly well suited to predictions based on phenology because, as cold-blooded animals, their growth and development is directly correlated with weather conditions, particularly temperature. The four major indicator plants used are saucer magnolia, common lilac, chicory, and Canada thistle.

January is a great time to select a few seasonal events or plant developmental milestones to begin tracking your property. It may not further climate change science, but it may help you feel a deeper connection to the world around you.

2 thoughts on “Phenology

  1. The best time to lay down crab grass preventer is when forsythia are in bloom. Earlier or later you are wasting your time and money. Personally I don’t any chemicals on my property, only compost and organic amendments, but thought I’d share this phenology tip with you. I have heard corn gluten is an organic crab grass prevented but have no experience with it.
    Rich Fischer.


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