The chill is starting to come on here in peach, plum and nectarine country. The leaves are off the trees in the orchards; there’s even a little fog here and there. That’s good news for trees as they get ready for the next year’s crop of California peaches, plums, and nectarines.

Trees need rest, just as we do. The cool weather is necessary for them to produce flowers and leaf buds in the spring - and after that, their crop of fruit. The amount of cool weather the trees experience is measured in “chill hours.” Each chill hour is an hour when the temperature is less than 45 degrees.

The right amount of chill hours help the tree “set” fruit. A successful set means that when the weather gets warm, enough blossoms will bloom and be pollinated to create a full crop of fruit on the tree.

A total of 800 to 850 chill hours between the beginning of November and the end of February is the desired minimum, but there are some early-season varieties that require as few as 350 chill hours, and some late-season varieties that require as many as 900 chill hours.