Making Wine in the Vineyard

Harvest is done, the wines are maturing and there is not much to do at the winery at the moment, WRONG.

 Time to get into the vineyards and start pruning, which directly affects the quality of the 2011 harvest.

But what is pruning and how do we go about it?

Pruning establishes how many buds remain on the vine, buds in turn create shoots on which clusters are carried. It therefore stands to reason that the greater the number of buds, the greater the potential yield. Sounds easy doesn’t it? There is more to this scenario than just meets the eye.

How many buds do you leave, what is the correct tonnage for your particular block of grapes? Well, that is dependent on the age of the vineyard, the soils on which they are planted, the density of the vines, the elevation of the vineyard as well as the direction in which the rows are planted. We can save this for further posts down the road, so let’s just stick to pruning for the time being.

Proper pruning creates a balance between the number of clusters and the vines leaf area. If not done correctly, your vineyard may be either over or under cropped, both of which negatively affect the quality of your fruit and thus the wine. Too much fruit, and the vine will not be able to properly ripen the fruit, too little fruit might lead to overly vegetative conditions, creating problems with shading.

At Keswick our vines are planted at a width of 9 feet with a spacing of 6 feet, meaning that we have 806 vines per acre planted. So how do we work out how many buds to leave?

By using the following formula

PY = (ANV x NC x CW) / 2000


PY = Predicted yield in tons per acre

ANV = Actual number of vines per acre

NC = Number of clusters

CW = Cluster weight

So if we pruned to 40 clusters per vine with a cluster weight of 0.23 lbs we would have 3.7 tons per acre using the formula above.

This is an ideal target, but at the moment we are pruning slightly higher than that to ensure we have enough buds on the vine in case we lose some due to spring frost and various other factors. During the course of the growing season, we will then move through the vineyard and get the tonnage per acre to exactly where we want it. 

What we are trying to achieve is the correct balance between quality and volume, ensuring the vineyard is able to produce fruit that will enable us to craft the best wines possible.

Kind of cool to think that what we do today, has a direct impact on harvest due to start in 6 months time.




3 comments on “Making Wine in the Vineyard

  1. Jay says:

    Do you look for different PY based on the varietal? For example, do you prefer denser concentrations of Verdejo v. Cab Franc? I’ve always wondered about that.

    • Jay

      Great question, we have looked at that as a possibility. Making the rows narrower is not an option as we already have the infrastructure in place, furthermore that would require the need for narrower equipment. There is also a question of cost and the fact that those vines will only start bearing fruit 3 years from now.

      The only thing we can possibly do is plant more vines in the rows and while that might be an option later on, in the meantime we are trying to prune back to ensure balance for our current planting density. There are a number of other things we are experimenting with first

      This year sees me taking over the vineyard on a full time basis and I would like to get to know the vineyard a bit more and concentrate on getting the vines we already have, producing optimally.

      We have some disease in the vineyard, and eradicating that is of number one importance at the moment.

      Hope this helps


  2. V says:

    Love this!!! It is nice that you are also spending the time writing this as well as pruning.

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