2026 Winter Injury Update

This post is an update on grapevine winter injury following an historic cold temperature streak in January 2026. 

Before I get into the details on bud injury here, a reminder: We will be discussing this information in more details at the Wooster Pruning Workshop on Thursday, March 12 from 1 to 4pm at Secrest Arboretum classroom 172 garden side (2122 Williams Rd, Wooster, OH 44691. Registration to attend is required. Please register at go.osu.edu/prune2026.

Recapping Statewide January Minimum Temperatures:

Several weeks of winter cold temperatures resulted in monthly average low temperatures between 5 to10 F colder than the 30-year long-term average (Figure 1). 

Figure 1. Average minimum temperature departure from the 30-year long-term average. Figure from CFAES Climate Office. 

This temperature departure was driven by persistent cold temperatures over the course of 2 weeks from January 24 to 31 (Figure 2).

Figure 2. Average minimum temperature departure from 30-year long-term average values for 26 January through 1 February 2026. Figure from MRCC.

With Lake Erie achieving > 95% ice cover by the end of January, the typically winter-moderated growing regions of Northeast Ohio lost protection of lake effect conditions to buffer temperatures. The Grand River Valley and Conneaut Creek areas were particularly impacted by temperature events reaching as low as – 14.6F (Figure 3).

Figure 3. Example of minimum temperatures on 31 January 2026. Temperatures throughout Ohio dropped below 0F over the week from 24 January through 1 February 2026. Figure from MRCC.

Bud Injury – Wooster and NE Ohio:

I am going to take this opportunity to once again highlight how significant site selection is when it comes to winter minimum temperatures.

• Elevation is one of the most significant contributors to localized minimum temperatures. Cold air follows elevational changes within a vineyard site (Figure 4).   
• Higher relative elevation can be several degrees warmer than lower elevational areas within the same site. 
• Matching cultivar cold hardiness to site conditions is critical to bud survival and capacity to achieve a consistent yield each season.
• Site-specific information is important to understanding how weather events may impact your vineyard risks for cold injury. This is only accomplished through tracking historical weather data with an accurate and appropriately located weather station. 

Figure 4. Site selection features impacting cold air drainage in vineyards. Figure from https://viticulture.uga.edu/files/2018/02/Vineyard-Frost-Protection-Extension-Bulletin_blog-share.pdf.

Armed with that information, let’s get down to the details of the damage. Over the past several weeks, our team at the Wooster Hort 2 and Kingsville AARS vineyards have been busy collecting canes from several different cultivars to assess bud injury.

Temperatures at Hort 2 in Wooster ranged between -7F at the highest elevational portion of the site (Block C) and as cold as -9.2F at the lower elevational end of the site (near Oil City Rd; approximately 20 ft of elevational difference between 3 different weather stations). Bud injury ranged between 5% (Clarion) and 36% (Teroldego; Table 1). Surprisingly, NY 06 and Frontenac blanc had higher rates of injury than I would have expected given their non-Vinifera parentage. However, the range of injury among all cultivars would be considered overall low to moderate.   

Table 1. Percentage of bud injury following -7 to -9F temperatures at the Hort Unit 2 vineyard at the CFAES Wooster Campus

Wooster
Variety	Primary bud injury (%)
Chambourcin	27
Cab Franc (FPS 11)	33
Teroldego	36
Regent	21
Crimson Pearl	9
Frontenac blanc	19
Clarion (MN 1220)	5
NY 06	33

 

Temperatures in the Grand River Valley were averaged across 4 different vineyard sites. Minimum temperatures fell below 0F on 3 nights from January 24 through January 31 (Table 2). Note: temperature variation across these sites also include use of active methods for cold protection (wind machines) during radiative freeze conditions. 

Table 2. Average minimum temperatures across multiple sites within the Grand River Valley for 24 January, 30 January, and 31 January 2026.  

AVE MIN (F) 24-Jan	AVE MIN (F) 30-Jan	AVE MIN (F) 31-Jan
-8	-14	-4.8

 

However, bud injury rates were largely consistent regardless of vineyard (Table 3).

Table 3. Percentage of bud injury across seven (7) representative vineyards in the Grand River Valley AVA (Ashtabula County, OH). 

Vineyard Site
Variety	Kingsville	Stoltz Rd	Rt 534	RT 307 (W)	S River Rd	RT 307 (E)	Conneaut
Cab Franc	82			58			55
Cab Sauv		54	66	71			58
Chamboucrin					46
Chardonnay		95	89	96		64	87
Merlot		98	99		100
Pinot Gris	77					55
Pinot Noir	76	90	55	37			61
Regent	15
Sauv blanc	82	91		73	75
Saperavi	82	68		84

*values indicate primary bud injury (%)

These values are based on an assessment of 100 buds per variety (10 buds per cane for 10 canes per variety). It is possible that vineyard sampling over-represents bud injury across a site. It is important to be as representative as possible and account for site-specific differences (e.g., elevation, slope aspect, etc.) within a vineyard block.   

2026 Pruning Primer

Evaluating bud damage using a representative 100 bud sample per variety (or across different vineyard blocks) can inform 1) retention of buds prior to pruning to maintain yield; 2) needs for possible retraining of vines if severe vascular damage has occurred; 3) potential yield loss and crop level expectations going into the growing season. 

How to dissect buds

We use a sharp, straight-edge razor (carefully!) to dissect buds along the cane by cutting approximately 1/3 of the way through the top of the bud perpendicular to the bud surface (Figures 5).  For an up-close video example, we recommend checking out this YouTube clip from Hans Walter-Peterson at the Cornell Finger Lakes Program: https://www.youtube.com/watch?v=eWtr0jzI2Dk

Figure 5. Bud dissection using a straight-edge razor February 2026.

What are you looking for?

When it comes to injury, green is good (alive) and brown is bad (dead). Below are examples of grape compound buds under a dissecting scope (18x magnification). Additional photos of bud dissection can be found at through University of Missouri Extension.  

Example 1. Compound bud showing the three interior buds (primary, secondary, and tertiary). Primary buds contain the largest fruit primordia (highest yield potential) and are also the largest of the three buds, followed by the secondary and tertiary (smallest, usually contains no fruit primordia). All three demonstrate green, healthy living bud tissue.

Example 2. This photo shows necrotic (brown) tissue of a dead primary bud. The color gives away bud injury in the absence of magnification. Note that the secondary bud is to the right of the primary bud in this photo due to the reversed orientation of the cane. The secondary bud sits to the bottom of the primary closest to the attachment point of the bud to the cane. 

Example 3. In this photo, it is only the secondary bud that is injured. In this scenario, the primary bud is still alive, and the status does not contribute to potential reductions of yield for upcoming growing season. However, if the primary bud (or shoot) is injured in a subsequent event, only the tertiary bud remains for vegetative growth (i.e., no yield). 

Adjusting bud retention during pruning

If you have not yet pruned, the following guidance can be used for yield retention following winter injury. This guidance is based on your individual percentage of primary bud injury. These recommendations are from Zabadal et al. (2008). Note that hybrid cultivars with fruitful secondary and base buds will produce a normal crop even with relatively high percentage of primary bud injury (e.g., DeChaunac, Marechal Foch, Seyval blanc, Vidal blanc). 

• If primary bud damage = 0 to 14%, then no adjustment of pruning is needed.
• If primary bud damage = 15 to 34%, then leave about 35% extra buds.  For example, if you prune to leave 30 buds/vine, and bud damage = 20% then leave an extra 35% or 40 buds/vine.
• If primary bud damage = 35 to 50%, then double the number of buds retained.
• If primary bud damage >50%, then it is best to minimally prune vines by hedging.