What is a Chill Hour in fruit plants?

1. Chill Hours are the minimum amount of chill required for the flower buds to break dormancy and to set fruit.
2. Chill hours occur between 32 and 45 degrees.
3. Chilling requirement is the total accumulating number of hours during the winter.
4. Each variety of fruit tree, bush and strawberry have a different requirement of needed chill hours
5. 
   

Southern varieties of fruit plants tend to need a lower number of chill hours than northern varieties.