Answer: That's a tough location with so little sun. Most flowering vines are tropical in origin and prefer more sun than the site provides. Here are some possibilities that can tolerate some shade:
Aristolochia durior (also sold as A. macrophylla) or Dutchman's pipe. Deciduous (will lose leaves in fall). Covers 15 x 20 in one growing season. Large, kidney shaped leaves are deep glossy green. Blooms late spring to early summer. Unsual flower is yellowish green, curved tube shape that flares into brownish purple lobes. Takes full sun to heavy shade, needs plenty of water.
Lonicera brownii, a deciduous honeysuckle, grows to 9-10 feet, with scarlet tubular flowers that can bloom from early summer to frost. Takes full sun or light shade and moderate water. There are many honeysuckle varieties, so check with your nursery for others.
Most clematis like their roots to be cool, with their tops in the sun. Clematis alpina, C. jackmanii, and C. recta are reliable performers.
Parthenocissus quinquefolia or Virginia creeper is a vigorous grower (30-50 feet) that takes sun or shade and regular water. Leaves turn bright to dull red in fall, but there is no flowering.
You might also consider trying an annual vine, such as sweet pea or scarlet runner bean, since you may want any light possible to come into the house during winter. Another possibility is a hardy climbing rose, assuming that thorns are not a problem in that location.
Hope these suggestions help you find just the right plant for your shady trellis!
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