Wisteria is a deciduous, twining climbing plant with a long flowering period and highly scented blooms. A Wisteria in bloom is a magnificent sight with long, trailing scented blooms which are either blue, purple, pink or white. Traditionally , Wisteria is grown on a south-facing wall. Wisteria rewards well, a beautiful climber flowering between April and June.
If Wisteria is growing well and happy in its spot, you may also get a second flush of weaker flowers in late summer around August time. I find this causes a bit of a pruning dilemma as those flowers can be just at the time of the summer prune and I hate to cut them off. Delaying pruning by a couple of weeks will make no difference in the long term.
Wisteria is vigorous, growing up to 9 meters (30ft) which means it needs a large space. It is not self supporting and requires a framework or wires or supports to grow up. Although Wisteria grows well in sun, and in full sun, it will also tolerate light shade. The downside to growing Wisteria is that it is a demanding plant to grow in terms of time and attention, labelled a red wheelbarrow plant.
There are no difficulties in getting Wisteria to grow because it is a vigorous climber; the trick is to get it to flower, (see below.) When planting Wisteria, it is essential to have a framework for the plant to climb up, secured with wires tied into the wall and hooks. The frame work is best put in place before the Wisteria is planted.
Wisteria floribunda (which twines clockwise) is originally from Japan, and w.sinensis (twines anti clockwise) is from China and is the more vigorous of the two. On W.senensis the flowers appear before foliage, and on W.floribunda flowers and foliage come out at the same time.
Wisteria requires pruning twice a year, (summer and Winter) to ensure it flowers consistently each year. Pruning is key to flowering. As the Wisteria matures, it grows further up the wall, ladders are needed for pruning which adds to the maintenance. Wisteria is vigorous and although it can be pruned to keep in size, it still needs a large space. It may sound obvious, Wisteria is best planted in the right place from the outset. This is because it forms very strong, woody roots and is hard to remove once established.
Wisteria blooms (racemes) come in soft shades of violets, pink and white. Suggested good varieties are: Wisteria floribunda 'Multijuga' which has scented racemes up to 1m long and is an attractive lilac colour and with the RHS garden merit award. A good pink variety is Wisteria floribunda 'Rosea' racemes up to 60cms long, scented and pale pink Wisteria floribunda 'Alba' is slightly less vigorous with white scented racemes up to 60cm and scented. The traditional Wisteria sinensis has strong colour and fragrance. If you have a large space and are looking for a striking garden feature, I have seen Wisteria combined with Laburnum growing over an archway to create a tunnel of lilac and yellow. Word of warning: Laburnum is poisonous and the seeds highly toxic so not a plant suitable for a garden accessed by pets or children.