Endowed with a constitution which enables it to withstand a degree of cold to which most other varieties of grapes would succumb, Janesville has made a place for itself in far northern localities. Moreover, it ripens very early, being one of the first to color though not ripe until some time after fully colored; and earliness is another requisite for a northern location. The vine, too, is generally healthy, vigorous and productive. But the fruit is worthless where better sorts can be grown. The clusters and berries are small, or of only medium size, while the grapes are pulpy, tough, seedy, with a thick skin and a disagreeable acid taste. Janesville has so many good vine characters that it may be of value for breeding purposes. It is fit for cultivation only in northern localities where better grapes cannot be grown or where fruit for a cheap red wine is wanted.
Janesville was grown by F. W. Loudon, of Janesville, Wisconsin, from seed secured at the Rock County Fair in 1858. It fruited for the first time in 1861 and was introduced several years later by C. H. Greenman of Milton, Wisconsin, who had bought the variety from the originator for $1000. It was named by the Wisconsin Horticultural Society in 1868. Janesville was placed on the grape list in the American Pomological Society fruit catalog in 1883 and is still retained. It is said by many to be a cross of Hartford and Clinton but this is a surmise and nothing is positively known as to its parentage. Its botanical characters are plainly those of a Labrusca-Riparia cross but with what admixture of the two species cannot be told. The early blooming season, and sometimes intermittent tendrils, indicate Vitis riparia, while foliage and fruit show both this species and Vitis labrusca.
Vine vigorous to very vigorous, healthy, hardy, productive to very productive. Canes spiny, intermediate in length, numerous, medium to below in size, dark brown; nodes flattened; internodes long to medium; diaphragm thick; pith intermediate in size; shoots thinly pubescent; tendrils intermittent to continuous, long, bifid to trifid.
Leaf-buds medium to below in size, short, thick, conical, prominent, open early. Young leaves tinged on under side and faintly along margin of upper side with rose carmine. Leaves small to medium, somewhat thin; upper surface variable in color, glossy and smooth; lower surface pale green, slightly pubescent; veins indistinct; leaf usually not lobed with terminus acute; petiolar sinus intermediate in depth, narrow, often closed and overlapping; basal and lateral sinuses lacking; teeth shallow, of average width. Flowers fertile, open very early; stamens upright.
Fruit ripens slightly earlier than Concord although it colors much earlier, keeps well. Clusters medium to small, short, of average breadth, cylindrical to tapering, usually single-shouldered, compact; peduncle short, slender; pedicel short, slender, covered with small scattering warts; brush dark wine color. Berries intermediate in size, roundish to slightly oval, dull black, covered with rather heavy blue bloom, usually persistent, firm. Skin thick, medium to nearly tough, adheres slightly to the pulp, contains considerable dark wine-colored pigment, astringent. Flesh pale reddish-green, translucent, juicy, very tough, rather coarse, vinous, sweet next the skin but quite acid at the center, fair in quality. Seeds adhere to the pulp, one to six, average three, above medium in size, broad, often angular, rather blunt, dark brown; raphe obscure; chalaza large, ovate, moderately distinct.