Hydrangeas can grow and bloom well even if they do not get direct sunlight. They will bloom best if they get several hours of sun though. However, if there is bright indirect light, H. macrophylla produces nice blooms. I have a few mac's and arborescens on a north facing wall where they get no sun and others where they get some sun in the summer. Both bloom well.

The area in your picture seems bright enough, so I would try some. Glyn Church recommends these mac's for shade: Immaculata, Marechal Foch, Mme. Travouillon, Parzifal, Quadricolor and Sister Therese.

It isn't as bright as you might think luis_pr.

What about Hydrangea quercifolia ('Snowflake'/'Snow Queen')? I understand quercifolia are able to do well ie flower in (lots of) shade.

Oakleaf hydrangea did not perform well (bloomage wise) for me when the shrub was planted near the drip line of a large tree. I re-read Glyn Church again and found this quote referring to oakleaf hydrangeas: best grown in a sunny site as too much shade will supress the bush and reduce the number of flowers but, a morsel of shade will be fine in hot climates.

Direct sun is not necessary but if you really think this location is very shady then consider (1) planting one shrub to experiment, (2) raise the canopy of the tree or lower the hedge to see if that helps or (2) try other plants. If you choose mopheads, make sure they will be fine in your zone or get reblooming ones.

Good suggestions 'luis'...thank you. Quantifying shade is so difficult isnt it? And I do think that I will need to experiment re those plants that are not true heavy shade plants. One never knows until one tries.

(I need a strike of lightning or two to thin out that tree at the back ;))