Thursday, March 22, 2007


As a fan of gardening and tromps through the woods, I was excited yesterday to learn the word phenology. What is phenology? First off, it isn't the study of head bumps as they affect personality (my that's a rather criminalistic skull ridge you've got there, buddy!). That's phRenology. Phenology... well, here's a website that gives a nice definition:

"Phenology is the study of the times of recurring natural phenomena especially
in relation to climate. It is recording when you heard the first cuckoo or
saw the blackthron blossom. This can then be compared with other records."

These days, phenology seems a bit tied up in the work of demonstrating that global warming is occurring. By comparing historic bloom times of certain plants over centuries, a trend is often visible. But the part that I think is so cool is that phenology allows 1) prediction of bloom times (Lilacs begin to bloom after about and 275 degree days, with a base temp of 33 deg F) and 2)coordination of agricultural insect control.

The UW Extension has this cool Phenology page which lists the degree days required for first bloom of certain plants, and first appearance of certain ornamental and vegetable pests. (Ornamental pests... I think I dated one or two of those in my younger days). So if you know your plant of interest is susceptible to a certain pests (say ash borers, with a larval stage at 275 degree days) and that dandelions start going to seed at around 275 degree days, you can wait to treat for ash borers until the first dandelions start going to seed (and the lilacs begin blooming). It's like a perfect blend of Old Farmer's Almanac folk wisdom and science!

PS: Degree days are like man-hours. If the set point is 50 deg F, and the outdoor temp is 52 degrees for 3 days, you've accumulated 6 degree days. And that's the problem with the UW page... no explanation of a set point. harumph.

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