How many clusters should I keep.

[lawrstin]

I have read anywhere between 44 clusters and 9 clusters per vine. This is dependent upon my vine spacing and density. I am growing Cabernet Sauvignon, can anyone give me a recommendation on a good formula to estimate the amount of clusters per vine to keep.

 

[Deezil]

There's multiple factors in this

Vine spacing/density, as you pointed out
Location?
How old are the vines?
What training system are you using?
Irrigation/water?

And then also keep in mind, you wont prune to your harvest-size on the first pruning. Vineyards do a few passes of fruit-dropping as the season goes on, basing the amount dropped on how the season is progressing..

If you drop too much, too soon, and the weather doesnt pan out - say those clusters raisin up, or mold over, or get attacked/eaten by wasps/birds.. Then you're short on your harvest

If you dont drop enough fruit, then the vine has a hard time ripening anything to a level that you'd want to make wine out of it

I wouldnt expect to perfect this ability on your first/second year of crops, I'm pretty sure its something you get a feel for as the years pass and one spends more time around the plants to learn what they are capable of

I'm sure I'm missing something, but I'm pretty sure there isn't any sort of formula to help with this

 

[lawrstin]

My vines are six years old. I started with a Scott Henry and I had trouble getting the vines to comb down. So I have been gradually converting them to VSP. I have nine feet row spacing. It's just a challenge to grow Cab in Oklahoma. I have opened the canopy up and I'm topping.

 

[GEM]

If your vines are in their second or third year, you are still wanting root growth not so much grape production. Rule of thu,b is to leave 8-12 clusters per vine at most. If shoots are below the first catch wire, I.e. less than 12-14 no fruit on them. Hope this helps. Gary

 

[lawrstin]

Gary, very helpful. That would basically allow 3lbs of grapes per vine. The twelve clusters times a quarter pound which comes to three pounds. I saw where a grower was harvesting between nine and eleven pounds per vine of Cabernet Sauvignon. Did I miscalculate? I am trying to decide whether I should cut a few or keep all my clusters.

 

[GEM]

If your vines are less than 4 years old, you should thin the clusters to what has been described. The energy of the plant needs to be directed to root growth, not berry ripening. Many growers in this area thin their clusters to get better flavor in their grapes as opposed to volume. I would error on quality as opposed to quantity, just my bias. I am on my 2-3d year and have thinned over 50 percent of the clusters. Gary

 

[TicinoVintner]

Since your vines are already six years old you shouldn't have to worry about root growth. You should thin first with spacing in mind, meaning take some that may be crowding each other to reduce disease pressure. If your going for quality then you shouldn't allow more that two clusters per shoot. Most only allow one cluster per shoot and I have heard of some who only allow one cluster per vine.

 

[lawrstin]

One cluster per vine? They must have a zillion plants in order to accommodate such a minimalist approach.

 

[TicinoVintner]

One cluster per vine? They must have a zillion plants in order to accommodate such a minimalist approach.

Pretty much. They space their vines 2 feet apart or less. When they prune they only leave a few buds per vine. Thats just too much work for me.

 

[blumentopferde]

I think that it is nonsense to talk about clusters per vine! As long as we don't know anything about the spacing of the vines! I'd rather talk about clusters per shoot (or clusters per m² if the clusters are distributed evenly amongst the shoots and the rows are not too far apart)!
And still that doesn't say much, as clusters differ very much in size. So we better talk about g/shoot or kg/m²!

But no, I have no formula on this.