How to determine growth habit without knowing variety

[Chingchongly]

I am trying to grow some grapes in my backyard as a newbie. I have a grapevine in its second year that needs to be trellised badly. My two options are VSP or TWC.

From what I've read, VSP is for upward growing varieties and TWC is for trailing growth varieties.

My question is: I do not know the variety I have. Is there a way to know whether a grapevine is upward growing or trailing, without knowing the variety? Are there tips or pointers that can assist with that? Can anyone teach me how to do that for myself when I go out there and look at my grapevine today? Would posting pictures here help you guys help me figure it out?

Thanks

 

[salcoco]

it is self describing. doe the grape have a tendency to drape on the trellis if so the TWC, if it grow upright then VSP.

 

[Chingchongly]

it is self describing. doe the grape have a tendency to drape on the trellis if so the TWC, if it grow upright then VSP.

I just came back from by backyard and was inspecting it very closely. If you give a horizontal surface for the shoots to rest on, they will rest on it. However, lateral shoots coming from that shoot are oriented upward. So does that make it upright growing?

I believe any shoot will start draping if it becomes long enough.

 

[BigH]

Here are some pics from my vineyard. I grow everything on a high fruiting wire (GDC or TWC). The first two are from Brianna, which is known for its procumbent growth habit (droopy and sprawling). The second two are La Crosse, which is the most upright variety I have. The blue arrows show laterals off of a main shoot. Notice how the Brianna is happy to send laterals horizontal or towards the ground, whereas the La Crosse wants to shoot them skyward. In the zoomed out pics, you can see that Brainna droops down nicely, whereas the La Crosse seems to fight heading to the ground. We are in a drought, so the La Crosse looks more upright than it normally would.

All varieties look upright when shoots are less than 2 feet long. Also note that I do shoot positioning to comb the shoots down. Before doing that, the Brianna loves to grow along the fruiting wire.

H

 

[efBobby]

Very informative, bookmarked!