Many fruit trees, as well as some bulbs and seeds, require a certain period of cold weather in order to blossom, fruit, grow, or germinate. What counts as a “chill hour” may differ from gardener to gardener, but most equate one chill hour to an hour of time a plant spends in temperatures under 45°F but above freezing (32°F). Keep in mind that growing low chill varieties in cold weather and high chill varieties in warm weather will cause problems with blossoming and fruit production. For seeds and bulbs, you can usually mimic chill hours with a refrigerator.
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