Great page on grape growing, with instructions

[Sue Sullivan]

for easy propagating from your spring trimmings:
http://www.extension.umn.edu/distribution/horticulture/dg1103.html

"Propagation

It’s easy to propagate grapes from cuttings. Take sections of the
canes from healthy, moderately vigorous vines while they are dormant.
This can be either in late fall or in early spring before growth
starts; early spring is preferred because once the cuttings have
leafed out and formed roots they can be placed outside, first in the
shade, and then planted out in the vineyard. Cut the sections directly
from the vine or from brush that has recently been pruned off. Make
cuttings three nodes long with the bottom cut (the portion that will
form roots) just below the bud or node and the upper cut at an angle
of about 45 degrees, ¾ to 1 inch above the bud or node (Figure 3).
Figure 3. Grape vine cutting.

grape cutting graphic

Plant cuttings as soon as possible after they are made. Place the
cuttings with the second bud from the top at soil level and cover with
loose soil. Rooting will be enhanced if the cuttings are placed in a
humid environment. After rooting has taken place, move the cuttings
outside if the temperature remains above freezing. Protect new plants
from direct sun. After the cuttings have adjusted to the outside
environment, they can be planted in the vineyard. It is important to
not let the cuttings dry out during this process. "