Freeze injury on grape flower buds and canes can cause crop loss and increased disease problems, but freeze damage at the graft union can kill the entire vine! The most effective technique for limiting freeze injury to the graft union is hilling up soil around the vines high enough to cover the graft union with 3 to 4 inches of soil. This practice is especially important for vines less than 5 years old. Now, before temperatures drop and the ground freezes is the time to get out there and hill up your vines. Factsheet 1264 https://njaes.rutgers.edu/fs1264/ details the following important aspects of hilling-up to protect the graft union from cold damage.
The principle of Hilling-up – How the soil works, both as a thermal mass that holds the heat and an insulator that slows heat loss.- How to perform effective hilling-up using available and specialized implements.
- Cost benefits of using the implements.
- Challenges such as timing, preventing damage to the drip lines and trunks during hilling-up; and how to address those challenges.
- The process of hilling down in the spring to prevent root formation above the graft union and proper weed management.
