My wisteria won’t bloom

Buds of wisteria, fattening up. They’ll bloom in two or three weeks.

The wisteria at the beginning of blooming. Once the wisteria is in full bloom, the leaves start to appear.

Anybody who has seen the long purple cascades of blooms understands the passion people have for wisteria: it is handsdown gorgeous. But the plant can take a long time to bloom, and even then, might not bloom much.

Wisterias are hardy to Zone 4, but the buds that become blooms won’t survive a late freeze in spring. In Winnipeg, Zone 3b, you may keep a wisteria alive, but it probably won’t ever bloom.

First, realise it can take several years for a plant to start blooming. From seed, it can take seven years or more before the first flowers are produced.

Second, know that your wisteria must get full sun to bloom. If it’s planted on the shady side of your house, forget it.

Third, don’t feed it and do keep it watered. Add compost if you like, but no chemical fertilizers.

If your wisteria has been in the ideal, sunny spot for a long time with no extra food and plenty of water, make sure you’re pruning it.

For pruning the tree or vine (depending on how you grow it), the hard part is done in late winter, around March. Prune out at least half of the previous year’s growth, leaving three to five buds per stem. Then prune it again in late summer to keep it under control. There are a lot of very detailed instructions out there for how to prune your wisteria, but if you follow these simple guidelines, it may bloom.

Finally, if nothing else has worked, try root pruning. About 18 inches from the base of the vine, take a spade and sink it into the ground, through the roots, about 8 to 10 inches. Do this halfway around the plant; which half doesn’t matter. Damaging the roots makes the plant think it might be dying and had best get to work on reproducing, which it does with flowers. Don’t worry, you won’t kill it.

If your wisteria still won’t bloom… well, green is a nice colour too. j