Re: HYB: germination - chilling hours

http://www.raintreenursery.com/chill_hours.cfm
http://www.raintreenursery.com/indexpics/chill-unit-map3.gif
Does not include Canada.
<Chill hours are roughly the number of hours between the temperatures of 32-45 degrees fahrenheit. Winter hours above 60 degrees are subtracted from the totals.>
These numbers are air temperatures for fruit trees. I'm not sure how this relates to seeds in dirt. Might be more if in shade & under reflective mulch, less if exposed. Map is a little hard to read, but I think 3400 hrs (~= 4.7 months of continuous chill in a fridge) is the most shown on this map. In northwestern Washington, extending into the farthest northwest corner of Oregon. Looks like Salem might be around 2800 hrs or (ta da) 3.8 months.
If vernalization of seeds can occur at warmer temperatures (i.e., 55oF), seems like the number of chill days could double. But I've not been able to find data for that. 

Linda Mann
TN
outdoor chilling = ~1300 hrs, according to map.

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