It's early yet! It's supposed to flower in April, and that's a generalization - could happen in May, in NH. It seems possible that the poorer flowering last year was because that was its first spring after being planted out.

If it really doesn't flower this year, then I'd suspect lack of light. It's supposed to be tolerant of part shade, but most plants with that sort of description really prefer more light.

Of course, if this is a grafted plant, it could be a bad sign that the graft is failing, but there would be more signs, like non-weeping stems growing from the base. (S. caprea is sometimes grafted onto non-weeping roots to produce a standard that weeps from some height, instead of the shrubbier form that is its natural pattern; or so I've read.) I think it may be too early to say whether that's what's going on.

Thank you for your respond!
I doubt it is too early. I already see small leaves instead of catkins, unfortunately :-((. It is not going to bloom this spring. Could "too much" fertilizer be a reason for not flowering?

Hmm. I don't fertilize trees and shrubs, so this is way out of my area. Why did you fertilize it?

Maybe you should have a soil test done. Your county extension service is probably providing this test at local garden-related events somewhere near you, and it's either free or costs just a few bucks. It's worthwhile to find out if the soil is ok, although willows are very adaptable and tolerant of a wide range of conditions.

If the shade is too deep, or the plant is too dry, it might not flower. You could ask or do a search on the trees forum, too, you might get more responses there.

Thank you for your help!