It sounds like you have hydrangea macrophyllas that bloom on old wood only. Do you know the name of the variety? Those hydrangeas develop invisible flower buds in late Summer that open in early Spring so any cold temps or late frosts can harm/kill the buds. Then you get dead stems and lots of new growth in Spring that will not bloom until the following year (if it survives winter).

The only solutions are:

* to prune soon after they bloom (they will develop flower buds some time after blooming so do not wait "too long"),

* do not over-fertilize (once in Spring is enough when newly planted and for 1-3 years; then only mulch and let it feed off the decomposing mulch afterwards,

* too much shade,

* winter protect when they go dormant in the Fall,

* try "rebloomer" macrophyllas (these actually bloom (1) in early Spring off last year's stems if any of them survived winter or (2) in early to late Summer off this year's new stems, provided that the new stems grew old and tall enough to develop flower buds and open them) or

* replace with Annabelle-like or Pee Gee-like hydrangeas if the rebloomers also fail to bloom reliably.

Actually bigleaf hydrangea produces flower buds that are noticeably larger than the terminal leaf buds and tend to be prominently positioned. Big dead buds at stem tips in spring would be a definite hint that your winters are too cold for the kind of hydrangea that you have.

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Thank you all.

That is a hydrangea macrophylla, a.k.a. big-leaf hydrangea, French Hydrangea, hortensia, mophead or lacecap. See the suggestions I listed above.

When does it get some sun (from when until when)?Do last year's stems leaf out or is all the foliage coming from new stems only?

When it begins to open blooms, you should see small broccoli heads.