Great hedge-nettle is an attractive perennial arising 70-150 cm high from a rhizome. The stem is erect and usually unbranched. The leaves are mostly on the square stems, where they are opposite. The leaves are pubescent on both surfaces. The leaves are deltoid-ovate to cordate-ovate in shape, the blades ranging from 6-15 cm long and 2.5-8 cm wide. The petioles are 1.5-4.5 cm in length. The margins are coarsely crenate.
The flowers are arranged in a series of verticels or whorls, the flowers being axillary to the leaves or bracts (on the upper part of the stem). The calyx ranges from 8-11 mm in length with glandular hairs and spine-tipped teeth. The corolla is a deep red-purple with a long tube ending in two lips, the lower lip being the largest. The tube measures 15-25 mm long and the lower lip is from 8-14 mm long. The anthers spread out flat.
Great hedge-nettle is found in swamps and moist low ground. It may be found from sea level to nearly 1100 meters in elevation in the lower mountains.
Great hedge-nettle is found from the Pacific coast east to the eastern base of the Cascade Mts. from southern British Columbia south to southern Oregon. In central Oregon, it is found in several locations to the east of Prineville, OR. in the western Blue Mts of northern Crook County. It is also found along Squaw Creek near the mouth of the Crooked River.