I have two grapes in my zone 4 property. One is a Valiant red and the other is a Niagra white. Both were grown in my forest garden and have straggled there way to minimal growth over the last 4 years. I have not pruned them and they have been growing among trees in a frost pocket of the forest.
None of this was ideal. This is what they looked like back in 2011, and is pretty much what they look like now.
|Valiant red grapes|
|Niagra White Grapes|
It will still have pure clay soil (hey, it's what we got!!) and will experience the type of wind that only the prairies can provide, but it's an improvement.
It will also have a fence, so I have decided to espalier it.
Here it is in April 2015 - pruned to two cordons.
|White Niagra Grapes Espalier on Fence|
Here is what I expect to happen and we will compare that with the actual results as they come in.
Each cordon (long horizontal-ish arms) should extend itself longer and send up new canes along it's length. I will allow those to grow all summer. In early spring/late winter 2016, I will prune those canes down. Most will be pruned to 3 buds to produce fruit. The others (every 3rd or 4th) will be pruned down to 1 bud to produce new canes for 2017. Spindly ones and the ones at the end of the "arms" will be removed.
In the summer of 2016 - these new canes should send out lateral branches that will bear fruit. The ones that were cut to 1 bud should produce 1-2 new canes each that will produce fruit in 2017.
In the early spring/late winter of 2017, I will cut off the canes that bore fruit in 2016, prune the newer canes down to 3 buds and 1 buds and the process will repeat.
At least, that's the way it's supposed to work. Come back for updates and to see if it worked as planned.