As average temperatures begin to drop in the late fall and early winter, plants acclimate to these cooler temperatures to reduce cold damage in potential cold snaps. With temperatures hovering from the mid-twenties to mid-thirties the last couple of weeks (Figure 1), tree fruit have had time to acclimate to the cooler temperatures.

This weekend, it is predicted to drop to the low teens. In preparation, we evaluated the cold hardiness of ‘Contender’ and ‘July Prince’ peaches to determine the lethal temperature for floral buds at the time they were collected (Figure 2 & 3, Table 1). 

Samples were tested for cold hardiness by collecting one year old peach branches and removing the floral buds. The buds are subjected to various cool temperatures ranging from 32 °F to -4 °F, simulating the drop in temperature during an evening. After the buds thaw to room temperature, damage is evaluated by cutting open each bud (Figure 4). A binomial regression model is fit to the data and the LT₁₀ , LT₅₀  , and LT₉₀ are calculated and plotted onto a graph (Figure 2 & 3).

Table 1: Lethal temperatures (°F) for 10% (LT₁₀), 50% (LT₅₀), and 90% (LT₉₀) floral bud kill in peaches.

If temperatures drop around 15 °F, minimal damage may occur. Temperatures as low at 10-11 °F may cause 10% floral bud mortality for ‘Contender’ and ‘July Prince’ peaches. And if temperatures drop closer to 5 °F, up to 50% floral bud mortality could occur. Damage may vary between variety, site, and location within an orchard. 

For commercial growers with questions or concerns, please reach out to Elayna Stirn, Brent Arnoldussen, or contact us through our social medias. 

12/10/2025

Authors: Elayna Stirn, Brent Arnoldussen