Determining Soil Temperature
Name: Gregory D.
Date: Wednesday, November 20, 2002
I have checked your site and found that grass
germination is best when the soil temp. is 50 to 60 degrees. My
question is this. If I were to take a soil temperature, at what level
should I measure? Surface, 1/2 inch below surface, 1 inch below,
etc? In the shade? Sun? Each level/location will give me a different
shade, and 1/8 to 1/4 inch depth
Anthony R. Brach, Ph.D.
Good question. I suspect that there is not a "standard depth". The optimum
germination temperature was probably determined in a lab or greenhouse where
the temperature is the same at any depth. You are correct, each
level/location is going to give a different reading. Another related factor
is moisture content, which also depends upon temperature. That is why
commercial re-seeding is often covered with a layer of straw to reflect some
of the sunlight and retain some of the ground moisture. The species of grass
also is an important variable. Winter rye, bluegrass, centipede, and so on
all have different "optimum" germination conditions. In addition, where you
live has an important effect on all of the above. I'd suggest you ask your
local agriculture extension office or garden store for a recommendation
relevant to your climate.
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Update: June 2012