Gardening: All about phenology

Nancy Szerlag
Special to The Detroit News

Mother Nature greeted me and the folks in my neighborhood with a colorful treat Easter weekend. The old-fashioned forsythia bushes suddenly burst into bloom announcing spring is truly on its way. They made my heart sing and I needed that.

For me and other growers of roses, the blooming of forsythia is Mother Nature’s way of announcing it’s the best time to prune the roses.

In Michigan, these bodacious bloomers tell us the temperature of the soil along with the  amount of moisture and sun is right to stimulate new growth of shrubs in spring.

The scientific term for the study of this annual phenomenon is phenology and it’s a  key component of life on Earth. It’s been studied for thousands of years.  

Magnolia and forsythia on a warm spring day in Michigan.

Hummingbirds and other species that migrate long distances return to their summer homes on a schedule that’s determined by the available food source along their routes. The same is true for butterflies. They don’t look at calendars 

Then with the development of technology and chemistry – tools and fertilizers along with the Gregorian calendar, “man” bypassed the science of phenology. Today monthly calendars of what-t-do-when abound in books, newsletters and websites.

However, scientists are finding with climate change and the alteration of seasonal patterns – temperature, moisture, and sunlight, the study of phenology, once relegated to the “the way Grampa did it”, may well be one of the secrets to saving the planet.

To find out more about the science of phenology and how it may help you become a better gardener and help our planet visit the website Budburst (

Another phenological tip:  Many chemical pre-emergent crab grass controls only remain active in the soil for a few weeks, so if applied too early it will not be effective. Blooming forsythias in your area tell you the soil has warmed enough for crabgrass seed to sprout so that’s the best time to use the product. Get the timing right and you shouldn’t have to use it season after season. If you’re planning on over seeding your lawn, read the crabgrass preventer label to see how soon after application grass seed can be put down.  Timing varies from product to product and formulas change, so don’t follow the mentality, “this is the way I have always done it”.  

Sad Note: Meredith Corp. to cease publication of its popular gardening magazine, Country Gardens. The summer issue due out in May will be the last. Strange, they continue to sell subscriptions on line and through the magazine.  

Nancy Szerlag is a master gardener and a Metro Detroit freelance writer. Her column appears Fridays in Homestyle. To ask her a question go to and click on Ask Nancy. You can also read her previous columns at