Extending the Vegetable Season in Tennessee: An Analysis of Minimum Temperatures and Freeze Probabilities

Although fruit and vegetable production accounts for less than 5% of the total farm receipts in Tennessee, it is a growing market. The value of production of tomatoes increased from $12.6 million in 1989 to $30.4 million in 1998. Other crops such as melons and peppers have had similar increases. Tennessee is characterized by mild springs and falls with warm spells interrupted by incursions of cold air. Therefore, either planting earlier or harvesting later than recommended can result in serious crop loss due to chilling or freeze injury.

The objectives of this study are 1) to determine the dates associated with probability levels (10, 25, 50, 75 and 90%) of critical minimum temperatures ranging from -4C to 13C in the spring and fall for about 100 locations in Tennessee and surrounding areas; 2) to examine the relationship between growing degree day accumulations in early spring with the risk of freeze; and 3) to make planting and harvest date recommendations for major vegetable crops based on risk of exposure to limiting minimum temperatures in both the spring and fall seasons.