Why have our wisterias not flowered?

Hazel Shoesmith, by email

Stefan says: You planted your two wisterias about five years ago to grow over an arch in your garden, in a sunny position at the bottom of a gentle slope. Since then, they’ve not flowered, but the leaf growth has been, as you say, fantastic. You were advised to give them sulphate of potash but that didn’t help. You prune them in August and also very early in spring.

You’ve done everything right so I can imagine the frustration. Switch to rose fertiliser in spring and also give liquid tomato feed every two weeks through next season. I give wisterias seven years to settle down, once planted, and if they’ve done nothing by way of flowering, then my suspicion is that they’re seedling plants and not a genuine named variety.