Vines usually need pruning to limit growth, to thin the stems and branches, and to remove dead or damaged wood. Some vines, such as honeysuckle, trumpetvine and silverlace vine, grow so fast and thick that considerable pruning may be necessary, while others need little pruning.
Prune most vines--including the summer flowering clematis, such as the Jackman's type--in the dormant season. The Florida and Patens types, including Clematis montana, blossom on one-year-old wood and should be pruned by thinning out in spring before growth begins.
Prune dead, diseased and damaged vines back to healthy wood. Interfering branches of woody vines, such as trumpet creeper or wisteria, should be cut back below the point of interference or all the way back to the junction with the main stem.
Prune out the top one-third of overgrown or elongated stems.
Prune by one-third or more old, mature stems that are declining in vigor. Each year, prune stems of bittersweet, trumpet creeper and wisteria to promote new growth and flowers. Prune back the tops of the plants to force out new branches. Silverlace vine should be pruned to the ground in early spring each year to produce vigorous new growth.
Considerable confusion exists about pruning wisteria. Tee two species most commonly grown are Wisteria floribunda (Japanese wisteria) and Wisteria sinensis (Chinese wisteria), both of which bloom before or with the unfolding of the leaves.
Pruning wisteria extensively during the dormant season may encourage rampant vegetative growth the next spring. Instead, in July prune out the long, straggly growth except those branches needed for climbing. This is more likely than anything else to induce flowering. Shoots should be cut back one-third to one-half their length. This will induce them to produce the short spurs that will bear next season's flower clusters.
Wisterias are normally vines, but pruning can make them take shrubby and/or weeping forms. Heading back young shoots holds the height at a definite point and after several years, the plant produces a trunk-like stem. Then leaders can be allowed to droop to the ground.
Wisteria will bloom abundantly if planted in good garden loam with full sun, watered well the first growing season and pruned in the summer.