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How do I prune wisteria to make it bloom? When should I prune?

Last Updated: Mar 15, 2017  |  36 Views

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Firstly, don't prune heavily in winter and early spring because you'll be pruning off flower buds and encouraging new (non-blooming) vegetative growth. You can improve flowering by pruning heavily after bloom time, in late spring or early summer. This practice reduces new vegetative growth and promotes flower production.

The flowers of wisteria may be white, blue-violet or deep purple, pink, or apricot, and are borne on lateral spurs on mature wood. These ornamental, deciduous, woody-stemmed, twining climbers have pinnate leaves and beautiful pea-flowers, borne in pendant racemes in spring. These plants look best on high walls and fences, on  sturdy pergolas or arches, where the flowers can hang down for best display. The espalier form is one of the best suited to display the hanging flowers. It will take three or more years to build up the basic framework of the plant to train in the espalier form. Once established, the aim of pruning is to control extension growth and to encourage the production of lateral flowering spurs. The current season’s shoots are cut back in two stages to within two or three buds of their base. These will bear the coming season’s flowers. Growth and flower buds are easily distinguished in late winter, the former being narrow and pointed, the latter plump and blunt. Pruning wisteria is best done in stages over a period of several years, removing one main branch at a time and tying in a suitable replacement shoot. The best time to prune would be midwinter, and again in summer, about two months after flowering.

Espalier training on a wall, securing with wire:

1) Start with staked plant. Cut back the leader to a strong bud about 30-36 in. above ground level. It is important not to cut below the graft union on grafted cultivars.

2) Remove any existing laterals to stimulate a strong new leader shoot.

Summer, year 1:

1) Tie in the leading shoot vertically to the wall by attaching  wire.

2) Select two strong laterals and tie them in at 45-degree angles. Prune any sideshoots to about 6 in., or three  or four buds to begin the formation of flowering spurs.

Winter, year 2:

1) Cut back the leading shoot to about 30 in. above the topmost of the laterals.

2) Lower the top pair of laterals and tie them into the lowest horizontal wall attached wires. Prune them back by about one-third of their length, to strong mature laterals.

Summer, year 2:

1) When allotted space is covered, continue to tie in the leading shoot.

2) Select the next pair of strong laterals and tie them in at a 45-degree angle.

3) Remove unwanted growth at the base or from the main stem, cutting out completely to its point of origin.

4) Tie in the new leading shoot of each lateral, and spur-prune any sideshoots to about 6 in., or to three or four buds.

Summer, established wisteria:

1) Continue to tie in the main lateral growths of mature wisteria and cut them back when allotted space has been covered.

2) About two months after the plant flowers, cut back laterals and sideshoots to within five or six buds or 6 in. of a main branch.

Winter (allotted space is covered):

1) Cut back the leading shoot to about 30 in. above the topmost of the laterals.

2) Lower the topmost pair of laterals and tie in to the nearest horizontal wire.

3) Prune all of the laterals back by about one-third of their length, to strong mature growth.

Winter, established wisteria:

Cut back the laterals and sideshoots pruned in summer to within two or three buds of their base. These will bear the coming spring season’s flowers.

Most wisterias flower best in a warm, sunny, sheltered site. Wisterias may take seven years or more to start flowering, and plants on nitrogen-rich soils may produce excessive vegetative growth and few flowers. Wisterias are long-lived plants and, if pruned annually as described above, seldom need renovation.

 

For tips on a variety of gardening topics, see our Plant Information Guides.
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Courtesy of NYBG Plant Information Service

 

Answered by Anita FinkleBookmark and Share

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