Chill hours refer to the number of hours a fruit or nut bearing plant requires in order to flower properly.  Chill hour requirements are genetically based.  These requirements keep a plant from blooming too early in its normal environment and suffering from bloom and shoot damage from the later freezes normally occurring in the area.

Chill hours are defined as the number of hours under forty or forty-five degrees.  There is some debate as to which number to use.  Also, using government supplied numbers, south Alabama is about eight hundred chill hours on average. But the government figures cut off chill hour calculations on February 15^th.  However, in some years, the nights have been much colder in March. Using a privately generated numbers up to April 1^st, we receive up to 1,200 chill hours.  During the middle of April 2008, temperatures dropped into the thirties setting low records for south Alabama, Georgia, and north Florida.

Use chill hours as a guide.  Always look for trees under 1,000 chill hours in our area, preferably 800.  In north Florida, close to the state lines, use trees under 700 chill hours dropping lower as you get closer to the coast.