When is Chicago's "growing season"?
Dear Tom,
Please define the "growing season." When does it start and end?
Gregg Dubin, Huntley, Ill.
Dear Gregg,
No single definition of "growing season" is satisfactory for all situations.
Generally speaking, the growing season is the period of the year during which air
temperatures remain continuously high enough for the growth of cultivated plants.
A commonly accepted standard is the number of days between the average dates of
the last spring and first fall occurrences of a temperature of 32 degrees. By that
measure, the growing season varies from 191 days (April 17 to Oct. 24) along
Chicago's lakefront to 162 days (May 1 to Oct. 9) in outlying suburban locations.
Ideally, the growing season should be defined biologically rather than
meteorologically because plant species vary greatly in their tolerance to cold
temperatures.