Ask-a-Dave's-Gardener: Optimum Soil Temperature for Seeds, 1 by mckinney3

mckinney3 wrote:
I subscribe totally to he notion that each variety of plant has a \"sweet spot\" for the best soil temperature for planting. The \"sweet spot\" maximizes germination rate and minimizes days to sprout and in general produces \"better\" plants.

ALL of the literature refers to suggested soil temperatures for each type of plant. My question is what does that really mean? For example, does 70 degrees F. mean that the lowest temperature over a 24 hour period is 70 degrees? Or does it mean that at some point during the day that 70 degrees is obtained. Or does it mean that 70 degrees is the average over a 24 hour period. Or ???

I have sub-soil temperature data-loggers \"planted\" in my garden so I can measure sub-soil temperatures on a 24 hour basis. In mid-April, the temperature cycle ( a nice sine curve) will range from 53 degrees to 67 degrees. So, what is the soil temperature for that day? =)