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Here is an article Constantin Voloaca wrote for the Canadian Grapes to Wine publication (Harvest Issue 2006).

Pruning Techniques for cold climate vines

Pruning

Dormant and “green” pruning are important components of the grape production system. Dormant pruning is by far more important than “green” pruning, providing the mechanism to maintain the training system, to select the fruiting wood, and to manipulate the potential quantity of fruit produced.

Assuming that the basics of pruning and training grapevines are relatively well known and understood, this paper will present some considerations based on my experience on growing grapevines under different pruning systems in cold climates.

Grapevines bear fruits on one year old canes grown from two year old canes. Many hybrids are also able to produce grapes on one year old canes grown from canes older than two years.
The main pruning systems make use of canes or spurs or a combination of both.

1. Cane based pruning system

a) Choose canes grown on the plant as close as possible to the soil.
b) The length of canes when trained should not overlap the canes from adjacent plants.
c) At the base of the plant, choose few spurs, based lower than the canes if possible, in order to provide new canes for the next year.
d) All undesirable canes and dead wood must be removed.

Advantages:
a) Snow winter protection.
b) Plant does not have to support (feed) old wood.
c) Early vegetation start.
d) Grape fruits may develop to the full potential (size and shape).

Disadvantages:
a) Laborious
b) Possible damage of canes from rodents..
c) Possible damage of some grape fruits from direct contact with the soil.
d) Difficult to apply herbicide during the growing season.
e) Following severe winters grape production can be compromised due to buds and cane frost damage.

2. Spur based pruning system

a) Each plant has one or two trunks and two arms. On the arm, prune canes back to 1-2 buds. Compensate for the number of buds with canes.
b) At the base of the plant at lest one spur should be kept for possible replacement of the trunk(s).

Advantages:
a) Easier to prune.
b) Shoots from the first 1-2 buds from the base of the cane begin their growth later in the season (at least few days) reducing the impact of late spring frost.
c) At the base of the one year canes (spurs) dormant buds provide new growth and even grape fruits if the principal buds are damaged by frost.
d) Uniform shoot growth.

Disadvantages:
a) No snow winter protection.
b) Grape fruits may not reach the full potential in regard to size and shape.
c) Arms have to be replaced from time to time.
d) Exfoliating bark provide shelter for diseases and insects.

Training grapevines

The grapevine training should provide the shoots and fruits equal opportunities for growth.
a) Canes should be trained as much as possible horizontally.
b) Train the shoots vertically.
c) Biodegradable tying materials should be used. They make next year pruning easier.