County-Specific Chill Hours Accumulation in South Carolina

Abstract

Winter chilling is critical for most temperate fruits and perennial plants during the winter season. Most fruit and nut trees require a prolonged period of chilling to break their dormant stage and bloom when spring arrives. This research’s primary objective was to calculate the chill hour’s accumulation in each county in South Carolina based on the historical hourly air temperature data for the last ten years (2010-2020). The chilling hours model used to calculate the daily chill hours was based on the number of hours when the air temperature was between 32°F to 45°F (0 to 7.2°C). The total chill hours for each county were then determined by accumulating the daily chill hours from October to June. Our results showed that among the different counties in South Carolina, on average Laurens County had the most prolonged chill hours (1419 hrs). The chill hours were higher between November to March, and counties near the coastal regions had fewer chill hours than the counties in the inland areas. For example, Beaufort, Charleston, Berkeley, Horry, and Dorchester counties that are located near the coastal region had fewer chill hours. In contrast, counties located in the inland areas like Laurens, Chester, Lancaster, and York recorded the most prolonged chill hours. Our results suggest that selecting high chilling requirement crops for the inland areas and low chilling requirement crops for coastal areas would be appropriate. Farmers in South Carolina can use this information to plan their crop selection and management.