Human Flower Project

Monday, April 30, 2007

Spring Happens, or Phenology

Last frost dates look too late to believe? After a mean final nip, “it” arrives right on schedule.

Last frost dates in the continental U.S.

(the line between light and dark greens is May 1)

Map: The Garden Helper

Phenology must be the oldest of the sciences, lots older even than its Greek name. It’s the study of natural phenomena, especially plant flowerings, bird migrations and mating.

Where we grew up, Louisville, KY, a widely accepted piece of folk phenology was the last frost date. No matter how balmy April might be, longtime gardeners warned you not to plant before Derby Day—the first Saturday in May. We’re not sure where Mystic Mom lives, but she writes, ” My Granddaddy used to say, ‘Never plant your ‘maters before Kentucky Derby Day.’ The Derby is Saturday so my ‘maters’ are going in the ground Sunday.”

Taking a look at more scientific measures of frost dates, we see that the old gardeners were right. The last frost in Shelbyville, Kentucky (a mite south of Louisville) is recorded as May 5, and this year that’s Derby Day on the dot.

Here’s a site where folks in the U.S. and in Canada can check on the last frost date for their locales. Sorry we haven’t succeeded in finding similar sources for other continents and countries. If you know of such, please send them along.

With global warming, there’s heightened awareness of phenology. Biological scientists are teaming up with amateurs around the world to witness and document the effects of climate change.

“It Happens Every Spring”

painting by Stephen Dinsmore

Image: Anderson O’Brien Fine Art, Omaha, Nebraska

A chronological smattering of last frost dates:

Berkeley, California * January 29

Ft. Lauderdale, Florida * February 1

Mobile, Alabama * March 19

Austin, Texas * March 21

Vancouver, British Columbia * March 28

Philadelphia, Pennsylvania * April 14

(Wouldn’t they say “Tax Day”?)

Quebec City, Quebec * May 13

Eau Claire, Wisconsin * May 26

Lake Placid, New York * June 19

Jackson, Wyoming * July 28 (!!)

The Greengirls of the Twin Cities had an interesting discussion of last frost recently. It seems in that part of Minnesota, the commonly accepted safe “mater” date is Memorial Day. Let us know of your own timetables, whether your phenology is scientific or vernacular, the Granddaddy kind.

(Congratulations to Stephen Dinsmore for his recent show at Anderson O’Brien gallery and for capturing the spirit of the season in this painting. The last frost where Stephen lives, Omaha, Nebraska, is May 12.)