Greetings from Glenway Vineyard!
Many of you might assume that the winter months are a slow time in the vineyard but nothing could be further from the truth. The months of January, February, and March are spent pruning the vines, and with four separate vineyards to prune, we’ve got our hands full!
The vineyard in winter.
Pruning is the first and most important step in a new growing season. The object of pruning is to reduce the number of potential ‘buds’ on each vine by removing approximately ninety percent of the previous year’s growth. A bud is the point on a dormant vine that will produce next year’s growing shoot. Each ‘shoot’ will produce the leaves and up to three grape clusters. At each point on a shoot that a leaf is produced, a new bud is formed. By the end of the growing season, there could be four to five hundred buds per vine. This is where balanced pruning becomes important. If too many buds are left on the vine, it will produce too many shoots and thereby, too much fruit. This can lead to a weak vine that is unable to ripen its crop and thereby lowering wine quality. If too few buds are left, the vine will grow too vigorously. Over time the vine will produce more vegetation than fruit and become inefficient. A balanced vine will carry an optimum quantity of fruit with just enough vegetal growth to fully ripen the crop.
This vine has the right amount of fruit but it is unevenly distributed. Note the empty spaces and bunching at the ends.
How many buds are left can vary from variety to variety and site to site depending on soil characteristics, nutrient availability and vigor potential of the vine. Generally speaking, each vine will be left with thirty to sixty buds. A proper bud count for any given vine can be determined by pruning the vine to its approximate size and shape and weighing the material that is removed. A formula is then applied to assess the actual number of buds to be left. For most European varieties, that formula is expressed as 20 + 20 or, 20 buds for the first pound of pruning weight removed and 20 buds for each pound after that. Therefore, a vine producing one and a half pounds of pruning material should be left with only 30 buds for the coming season. Taking pruning weights from a percentage of vines in a given block within the vineyard and averaging those measurements can determine an ‘average bud count’ that should be achieved in that block.
An un-pruned Cabernet Sauvignon vine.
Here in Virginia, the most widely practiced pruning method at this time is referred to as ‘cordon trained/spur pruned’. This is the method used in our vineyards. It consists of two permanently trained horizontal arms called ‘cordons’ on either side of the trunk that are trained to a primary support wire. At 3 to 4 inch intervals along the cordon, a ‘spur’ is left to provide the fruiting wood. Spurs are created by pruning back the previous season’s ‘shoots’ and are generally 2 to 3 buds in length.
The same vine after pruning. Note the cordons trained horizontally with spurs pointing up.
While many large scale vineyards use machines to execute some or all pruning operations, this critical step is always performed by hand in our vineyards. Hand pruning requires highly skilled personnel and many hours of hard work, often in extreme temperatures and weather conditions. A keen eye and intuitive knowledge of the vine is paramount, as proper pruning is the single most important step in controlling crop levels and ultimately in producing premium quality fruit. Our goal is to create a vine that is balanced and healthy for many years to come.
Until next time, here’s looking forward to a mild winter and bountiful season.
Tom Kelly, Vineyard Manager
