This is a grape of Austrian origin having been crossed by a fellow by the name of Fritz Zweigelt in the early 1920's. The vine is a cross of Blaufrankisch and St. Laurent. The vine is a very heavy producer and can crop at 5-6 tons per acre.
references suggest that this vine has late bud break and is relatively early ripening, a few days before Pinot Noir and a week after Regent. The vine is also reported by some who grow it (Peter Salonius and Paul Troop) to have some practical mild disease resistance to the common mildews and is relatively cold hardy to approximately -20c. The grapes from the vine is also reported to make very good wine and the Zweigelt I've tried from Arrow Leaf cellars in BC is quite good - of course this is subject to the skill of the winemaker and quality of grapes.
We've got a few Zweigelt vines planted at the test vineyard now after acquiring some cuttings from Paul Troop of Omega Vines (see links on the blog) in the spring of 2010. In general the vines are strong and vigorous, and we'll see how they make out the winter and bud out next year.
This vine is suited for only the best location at our site with the longest frost free days and greatest accumulation of degree days. This would be on the upper bench which is about 100 feet above the test vineyard. The upper bench appears to average about 10 percent more degree days. Our test vineyard seems to be averaging about 140-145 frost free days and 900-950 degree days so it could be extrapolated that the upper bench has about 1000-1050 degree days and perhaps a slightly longer frost free season.
This frost free days and degree days status of the test vineyard is likely not enough for this variety based on trials at Mt. Vernon, Washington where 1000 degree days is recommended. Also, a grower in New Brunswick gets about 900 degree days and 140 frost free days and it barely ripens most years. As such, I've planted one of the Zweigelt vines on the upper bench and will use that to compare the growth stages with that of those in the test vineyard. Going to add a few of the other varieties up there as well (Castel and perhaps transplant one of the Pinot Noir as well) again to see the difference in growth stages between those on the upper bench and those in the test vineyard.