CFAES Give Today
Buckeye Appellation

College of Food, Agricultural, and Environmental Sciences


Posts By Date

By: Maria Smith, HCS-OSU

Following last weekend’s warm weather, bud break has arrived in many early varieties (e.g., Marquette, La Crescent, Itasca, Marechal Foch). These varieties are now more vulnerable to freeze and frost events since more developed shoots are progressively less tolerant of temperatures below 32 F (Figure 1, Table 1).

A close up of a branch with water drops on it

Description automatically generated with low confidence 

 Figure 1. Bud break, E-L stage 4, Monday, April 25, 2022. Photo credit: Diane Kinney

Table 1. Estimated critical temperatures (°F) of Pinot noir at different stages of bud/shoot development



Bud break

First leaf

Second leaf

Third leaf

Pinot noir







Once again, Ohio is forecast for widespread frost and freeze through Saturday (Figure 2).



Description automatically generated

Figure 2. Freeze warnings and forecast temperatures for Apr 27, 2022. Figures from

Thanks in part to the persistent cold temperatures throughout March and April, overall bud break is behind where we were at this time in both 2020 and 2021, which means total expected damage should likely be lower relative to the past 2 years. However, if your vineyard might be affected by the upcoming frost/freeze advisory, reviewing options for protection may be helpful in mitigating damage this week and in future spring cold injury events.

Be prepared - Resources on spring frost protection and recovery:

Spring frost is a topic we have covered extensively in 2021 and 2022. We have republished guidance here, and more detailed information can be found in the newly published Bulletin 920: “Spring Frost Injury of Grapevines and Protection Methods”

Methods prior to frost event

  • Delayed pruning: similar to 2020, vines have more advanced phenology than normal and buds are pushing earlier as a result of above average temepratures. Delayed pruning helps with delaying budbreak.
  • Double-pruning: the rationale is similar to delayed pruning. With 1st pruning, you leave extra buds per vine. Due to apical dominance, apical buds push earlier than basal buds. If frost occurs, basal buds (which are delayed in growing) will be less likely to be injured. With the 2nd pruning, apical shoots (injured or not) will be pruned by retaining a final bud count per vine. Note: the 2nd pruning should occur when apical shoots are less than 2" in total growth to avoid potential issues with fruitless shoots developing from the basal buds regardless if you are past the last date of freeze.
  • Row middle and cover crop: bare ground in row middles provide more heat to keep vines warm during a frost event. Mowed grass cover crop will also do the same. So, it is crucial that you mowed your grass as short as possible for added frost protection.
  • Products that delay budbreak: Some products can be effective, but it is too late to apply now if you have not already done so. Please view the recorded webinar presentation with Dr. Imed Dami (link) for an overview of the available budbreak delay products.  
  • KDL (0-0-24) fertilizer: Even though growers would like to use this product, research has shown that KDL does not protect shoots against frost injury once vines resume growth. Therefore, it is not recommended. Dr. Smith researched this product and can be contacted directly for more information.
  • Copper: has been shown to protect young shoots against frost injury by killing ice forming bacteria present on vine foliage. You may start spraying as soon as budbreak and repeat every 5-7 days (washes off easily and must be reapplied after an inch or more of rain) until you’re out of the frost threat period (2 – 3 weeks) in your vineyard. Read the label for the application rate. In CA, 0.75 actual copper per acre was used. Read the label to avoid plant injury. To avoid injury, apply when not cold or wet (slow drying) and use formulation with lime.

Methods during a frost event

  • Wind machines: wind machines, although expensive, are effective against radiative spring frost events (clear, cold nights with temperature inversions).
  • Overhead irrigation (sprinklers): None of our growers in OH has this system. Having said that, DO NOT SPRAY YOUR VINES WITH WATER USING A SPRAYER. You will cause more damage than doing nothing.
  • Heaters: same as above; not a common method in Ohio. When temperature inversion exists, heaters are effective alone and best with wind machines. However, cost of fuel and pollution are main limitations.

Since threats of below freezing temperatures can persist into May, it is a good idea to also review the recommendations for managing the vineyard in the event that freeze causes shoot injury. Those recommendations can be found in the APRIL 2020 OGEN.

Posted In: Viticulture
Tags: 2022 Season, Spring Frost
Comments: 0