Definition - What does Dormant Pruning mean?
Dormant pruning is done during the dormant season of the grapevine, ideally during the winter months between January through the beginning of March. When dormant pruning gardeners should remove 70-90% of the wood canes and growth produced during the previous growing season. All canes that are over a year old should be removed and any surplus one-year canes that distract from new growth or canopy positioning.
WineFrog explains Dormant Pruning
Dormant pruning is important because it removes old growth, maintains the vine training system in place and allows the vintner to make selections of fruiting wood and manipulate the new growth during the next season. Grapevines must be pruned annually and usually done after the first of the year to prevent exposure to freeze/cold injury. Vine balance is the most important aspect of pruning because it influences the amount of crop yields and to regulate the number of shoots exposed in the canopy. It is also used to remove any parts of the vine that may be infected with diseases. Each year after original plantings should have a specific dormant pruning plan to establish the vines and renew fruiting potential. After pruning, all cuttings should be removed and all tools should be sterilized to prevent any spreading of disease to new crops.