The forecast for New Jersey statewide is expected to drop below freezing Tuesday and Wednesday overnight into early morning this week. Fruit crops are most vulnerable in the full bloom to petal fall stages.

Figure 1. Peach bud development stages and corresponding critical temperatures. Adapted from MSU Fruit Extension. Photos by H. Gohil.

Temperatures beginning at 28°F can kill 10% of the flowers when in full bloom and 90% of the flowers when temperatures drop to 24°F or below for more than 30 minutes (Figure 1). Please refer to your local forecast at nearby weather stations to receive the most accurate temperatures during this time period at www.njweather.org/ or https://newa.cornell.edu/.

Management Options for Frost Protection

• Cloth coverings – This can be an effective tool to protect a small number of trees. Sheets, burlap, or frost blankets can provide some protection. Avoid plastic tarps which do not provide efficient insulation and can increase freeze damage on plant tissue. Ensure the covering reaches the ground.
• Irrigation – Irrigate the soil under the trees the day before so any heat will be absorbed. Overhead irrigation is an option if available. The irrigation must stay on until ice starts to melt.
• Heaters – Heat can be sourced through burning propane, natural gas, or oil burning Smudge pots. This could be a valuable investment for a commercial orchard that experiences frost events at critical bloom times; however, it is expensive and highly inefficient as heat produced dissipates quickly.
• Wind machines & helicopters – These devices can be used in conjunction with heat or alone to mix warm air from higher elevation with cold air in the orchard.
• Frost Rescue Sprays – Plant growth regulators such as Promalin can be applied to apples and pears following a frost event to help increase fruit set. The application must be made within 24 hours of the frost event and the trees must be thawed. Follow the label for use restrictions.

References

Gohil, H., Muehlabuer, M., Polanin, N, and Crassweller, R. (2020). Active Frost Protection Methods for Your Orchard. Rutgers Cooperative Extension Bulletin E363. https://njaes.rutgers.edu/e363/

Gohil, H., Muehlbauer, M., Besancon, T., and Ward, D. (2025). Preparing Orchards Against the Frost – Low Tech Strategies. Plant & Pest Advisory Rutgers Cooperative Extension Preparing Orchards Against the Frost – Low Tech Strategies — Plant & Pest Advisory

Demchak, K. (2020). Frost and Freeze Damage on Berry Crops. PennState Extension https://extension.psu.edu/frost-and-freeze-damage-on-berry-crops