What Happens to the Vines During Winter?
Spring and summer are where all the action is for grapevines but fall and winter are equally as important for the well-being of the vine, albeit a little boring at times. Like deciduous trees, grapevines lose their leaves in the fall, the sap travels primarily to the roots, and the vine goes dormant. Another way of looking at it is to say that the vine is sleeping.
During this time, the vine is not producing shoots, leaves, or grapes. Instead, it is saving up all its energy for the coming spring where it will once again burst forth with grapey goodness. But just because the vines are asleep doesn’t mean that grape growers can take a break. With all the leaves gone, winter is a great time to assess the health of the vines. It is easier to see cordons and shoots and how they grew during the spring and summer will influence how the grape grower will prune back for next year. Excess rain during the fall could mean that early application of fungicides is necessary. Another thing to look out for is those pesky freezes. Because the sap has moved to the roots, a fully dormant vine is fairly well protected from freezes and cold weather. At least it is in regions where the cold weather is more predictable.
One of the challenges of grape growing in Texas is the wonky weather. Because most parts of Texas rarely see temperatures below freezing for an extended period of time, the grapevines do not always go fully dormant. An advantage of this would be that the vine expends less of its energy stores “waking up” in the spring, thus having more energy to make good grapes. The disadvantage of this is that if Texas does have a snowpocalypse the sap that is left in the trunk and cordons could freeze. This freezing sap expands and damages the cellular structure of the vine. The damage could be minor, and the vine may be able to heal on its own or it could be catastrophic, and the vine could die. There is no rest for the grape grower, and we can not make great wine without happy healthy grapevines.