The grapes grown on the Pacific slope are almost exclusively vinifera varieties, though a few American grapes are planted in the Pacific Northwest.
"Manual of American Grape-Growing"
U. P. Hedrick
A few varieties of native grapes fare badly in the winter's cold of northern grape regions, and the tender vinifera vine is at the mercy of the winter wherever the mercury goes below zero.
"Manual of American Grape-Growing"
U. P. Hedrick
The following spring the vinifera roots are cut off below the graft and the top of the stock above the graft is removed.
"Manual of American Grape-Growing"
U. P. Hedrick